In its original conception, the United States uses a federal system of government. In theory, this means that the States hold general police power over all crimes, while the national government has only the enumerated powers set forth in the United States Constitution to address very specific criminal acts. These included power over crime between different states, crimes affecting interstate commerce, criminals who cross state lines, or crime committed by members of the national armed forces, or crime that crosses the international borders.
Hang with us. The theory was the easy part.
The hard part is, the theory has been complicated by 2+ centuries of judicial precedents. Simply put, these are legal cases in which the decision by the court establishes a new rule or principle that other courts follow from that time on. Of particular importance to criminal law, as well as to many other areas of law, is the broad reading that courts have given to "Commerce ... among the several States," which now means just about anything that could at least theoretically affect such commerce. There have also been Constitutional Amendments that affect the original concept (notably the 14th Amendment). Finally, the practical application was somewhat complicated by what some Americans of Southern heritage still refer to as "The Late Unpleasantness". All of this has granted all American police agencies a huge amount of power, far beyond anything imagined by the folks who drafted the Constitution. And as we will see, there is an astounding array of US police agencies. While there are significant differences amongst them, all have several things in common.
- First, unlike some other police services such as Britain's, the law enforcement agencies in the US issue firearms to their officers as a matter of course. Every sworn member of every agency listed after this carries (or is authorized to carry) a gun. Sworn members are those who have taken an oath to uphold the US Constitution, their state's constitution, and the laws of their particular jurisdiction; in addition to carrying firearms openly or concealed, these officers are also those empowered to make arrests. The firearms carried vary from jurisdiction to jurisdiction and, to a certain extent, by historical era as well:
- Until the late 20th century, most officers carried 5 or 6 shot revolvers chambered in .38 caliber or .357 Magnum, and Colt or Smith & Wesson were the manufacturers of choice. This was mostly because, contrary to what you might think, police departments assumed no familiarity with weapons with their new recruits, and the "wheelgun" was much easier to learn than most semi-autos of the day. The long association of revolvers with the police, of course, helped create the Revolvers Are Just Better trope. However, one of the things the Dirty Harry series got right was the rarity in law enforcement of the "most powerful handgun in the world;'' most officers saw the increase in firepower of the .44 Magnum (and later, even more powerful handgun & cartridge combinations) as not being worth the vastly increased hand strength and target practice necessary to handle one well.
- More or less concurrently with the "War on Drugs" (and the emergence of well-armed drug dealers and bank robbers wielding submachine guns and assault rifles) departments across the country began switching to semi-automatic handguns with 10-, 12- or even 17-round magazines, usually chambered in 9mm or .40 caliber. Glock, Beretta, and Sig Sauer seem to be the most popular brands. The event that helped trigger US police forces getting More Dakka was the infamous North Hollywood Shootout. It caused many American police forces to conclude that many of their standard armaments at the time were insufficient. The two shooters tooled themselves up with assault rifles and body armour, the former of which gave them a massive amount of firepower compared to the standard-issue pistols and shotguns of the responding cops, and the latter which allowed them to No-Sell most of what the police did manage to throw at them. Several officers ended up borrowing some AR-15 rifles from a nearby gunshop in order to try and fight back. In the end, Larry Phillips was shot eleven times (including the self inflicted gunshot wound that killed him), while Emil Mătăsăreanu was shot 29 times and took over an hour to bleed out when he was finally apprehended. Many police departments began arming their officers with greater firepower in response to the incident.
- Before that was the 1986 FBI Miami shootout, wherein Michael Platt managed to shrug off about a dozen rounds fired by the agents .38 and 9mm pistols (several of the guns the agents were using were actually .357, but loaded with .38) to kill two agents and severely wound several more before the massive amount of gunshot wounds he sustained finally caught up to him. The combination of poor stopping power, the difficulty in reloading a revolver without speed loaders in combat (and that's not including several of the agents having been shot in the hand and trying to reload) and advancing technology led to the FBI adopting new magazine fed pistols, and also led to the creation of the .40 S&W.
- Almost all jurisdictions also traditionally provided pump-action shotguns, usually in 12- or 20-gauge, as standard equipment in patrol cars. Since the late 1990s (in response to some high-profile shootouts with criminals wearing body armor and carrying automatic rifles), the increasing trend has been to train and equip more and more officers with AR-15-pattern semi-automatic rifles or carbines as standard equipment on patrol.note The shotguns are still issued as well, as they are better for some situations than a patrol rifle, hence a modern patrol car or SUV will generally have a gun rack with both locked in.
- Special Weapons And Tactics teams, as you might expect, use even more specialized lethal weaponry, including Sniper Rifles and even fully automatic weapons. And undercover officers may use almost anything that's easily concealable.
- Sworn, uniformed officers also carry one or more of a selection of non-lethal weapons. The old-fashioned nightstick is still around, but many departments have replaced it with the single tonfa or collapsible "Asp"-type batons. Chemical ('pepper') spray and tasers are also becoming more common. Nevertheless, since these weapons are only designed to be non-lethal, and have in fact killed people who suffered from certain medical conditions, their use is controversial as well. Further, because these weapons — except chemical sprays — are not easily concealable, most plainclothes and all undercover officers only use firearms. Riot-control and SWAT teams also readily use specialized equipment such as flashbang grenades, tear gas, rubber bullets, riot shields, and have been experimenting in recent years with sonic or microwave weapons.
- When those officers may be armed, technically, varies. All departments require their officers to be armed while "on shift" — during their designated working hours. Some departments require that their officers carry at all times, and virtually all encourage this. Further, a 2004 Federal law, the Law Enforcement Officers Safety Act, allows qualified current law enforcement officers and qualified retired law enforcement officers to carry a concealed firearm in any jurisdiction in the United States, regardless of state or local laws, with exceptions.note
- However, it is not true that every employee of a US police department is armed. Virtually all of the following agencies also have "civilian" or unsworn employees, who typically make up at least a quarter to almost half of an agency's staffing (and in the case of large federal law enforcement agencies, such as the FBI, the number of support staff exceeds the number of sworn law enforcement personnel by as much as two-to-one). These include dispatchers (the communications personnel who receive 911 calls and send radio calls to the police), crime scene analysts, and forensic technicians. Examples in recent fiction include Abby and Maddie, Barry Allen and Edward Nygma, respectively.) These employees usually are not authorized to make arrests or pack heat in an official capacitynote .
- Other unsworn employees of police departments, especially large ones, can include psychologists and counselors, secretaries and clerks, victim's advocates (who are trained to work with crime victims), IT staff, technicians, carpenters, mechanics, pilotsnote , accountants, lawyers, intelligence analysts, translators, media production, public relations specialists and all the other various administrative staff that any large, complex government agency needs to function.
- Second, the sheer size of the United States (for quick comparison, Texas, the 2nd largest state, is roughly the same size as the nation of France; Rhode Island, the smallest, is almost twice the size of Luxembourg) has made the automobile an equally indispensable part of police life. Police cars in the U.S. may be either marked or unmarked. While marked police cars in most countries run the gamut from minicars to near-exotic sports models, American cops favor big (and we mean big), preferably rear-drive and V8-powered sedans.
- For many years more than ninety percent of cop cars were the mighty Ford Crown Victoria (preferably in pursuit-ready P71 Police Interceptor specification) - Everybody Owns a Ford as almost literal Truth in Television. Further, the Ford Mustang (and some other US "muscle cars") were historically used in high-speed pursuit/intercept and highway patrol roles). The Crown Victoria was discontinued after the 2011 model year, however, and replaced by police-spec versions of the Ford Taurus and Fusion (which have since been discontinued as well). As the Crown Vics age out of service, other models have risen in popularity. Ford itself claims that its Taurus police model and its "Interceptor" brand of the Ford Explorer together sold almost 25,000 units in 2014.
- Other manufacturers angle for their share of the police market in different ways. The Dodge Charger was already a real competitor to the Crown Vic, due to it being more powerful, maneuverable, comfortable, and notably, not a 30-year-old design. It does share, with the Vic, a thirst for fuel.
- GM contributed the now-phased-out 1991-1996 Chevrolet Caprice, its last domestic full-sized sedan and a platform that makes the Crown Vic look modern. From 2012 to 2017 General Motors imported a police package version of the WM-series Holden Statesman as the next-gen Caprice, which was praised by officers for combining the interior space and power of the Crown Victoria with the handling prowess and slow-speed maneuverability of the Charger, but failed to catch on due to its high asking price and the "Buy American" (or at least, "Buy NAFTA") rules in place in many jurisdictions. Also, in many northern states, the Chevy Impala has become a common sight, due to the fact that it has front-wheel drive - not as badass as rear-wheel drive, but much more useful for driving in six inches or more of snow. Oh, and it's also more fuel efficient than the heavy Crown Vic and the big-engined Charger.
- Most departments, insofar as budgets allow, consistently choose a single model for their standard patrol cars; not out of brand loyalty, but because of the demands of police pursuit/emergency/high-speed driving. Even subtle model differences require different driving techniques, and the difference between rear-wheel drive and front-wheel is enormous. Thus, it's more efficient to have all officers learn and operate on the same model.
- Recently, an increasing number of police departments are using SUVs (usually the Ford Explorer and Chevy Tahoe) and pickup trucks (Ram Trucks and Ford Super Duty being the most common) as full-time patrol vehicles as well.
- Some departments assign a patrol officer her or his own particular car; an officer can drive such a car home and add a certain amount of individual accessories, as long as said gear does not detract from the uniform appearance of the vehicle. Other agencies have car pools, which does not refer to officers riding to work together. Rather, it means the department keeps the marked vehicles at the station, and as officers come onto and off shift they are assigned in and out of one of the pool of cars. Fewer individual choices, but the officer bears less of the responsibility also.
- Unmarked cars used by uniformed officers (Yes, this is common, often for highway patrol duty) tend to be the same models as the marked ones, which makes spotting them easier than the cops would like. However, undercover officers can and do drive anything, because many of their vehicles are cars impounded from their owners for various offenses.
- Jurisdictions that have K9 units (not that one) have special transportation needs; since a K9 team is one human officer and one trained police dog, they need a little more legroom. Therefore, many use SUVs and station wagons instead. Those vehicles usually have special markings in addition to the standard departmental paint job, such as an added silhouette of a dog's head and/or a large K-9 emblazon. Departments with horse-mounted officers use pickup trucks and trailers to transport their mounts from stables to deployment areas, which means they are using one form of transport to haul another. However, these horses and dogs are not considered mere tools by their human partners; for the vast majority, the animal very nearly becomes a Non-Human Sidekick. Further, most states consider an assault against a police dog or horse a felony, and federal law enforcement animals are protected by the Federal Law Enforcement Animal Protection Act.
- There are also other vehicle types for specialized purposes, such as large SUVs for rural departments, hybrids or electric cars for parking enforcement and city patrols, vans for evidence techs and SWAT teams , and so forth. Jurisdictions with extensive waterfronts will have police boats of various kinds; agencies with lots of square miles to cover will have helicopters and possibly fixed-wing aircraft; and police motorcycle units are commonplace. Some departments, especially in urban areas, have bicycles as well; the belief is they provide as much community contact as old-fashioned walking the beat, but give the officer both more speed and the ability to cover a greater area. And, yes, the Segway is also in use by "real" police departments, not just mall cops.
- Finally, contrary to some urban legends, citizens are not automatically at fault in the event of a motor vehicle accident involving a police vehicle or even an officer—in fact, many jurisdictions automatically assume the police officer to be at fault unless proven otherwise. However, if you are involved in such a crash, virtually every department has rules in place that prohibit the officers from working an accident involving "one of their own." In other words, a city cop would have to wait for a county deputy or state patrolman, and vice versa. In overworked departments (most of them) and large jurisdictions (almost as common), this can involve a long wait — although other first responders don't have to wait for the police.
- Third, Post 9/11, one trend police forces in general seem to be following is equipping themselves with secondhand military grade gear. Due to a number of anti-terrorism policies set forth by Congress, police departments may request to be equipped with surplus military gear such as body armor, assault rifles, and armored vehicles such as Humvees. Critics claim it has reached the point where some police departments have become virtually indistinguishable from a military unit, at least in terms of hardware, but some of this perception is due to mixups, such as the army forgetting to remove the heavy machine guns from an old Humvee. Any local police department can take advantage of this, regardless of location or size. Police agencies also increasingly cross-train, certifying officers as SWAT or other specialized "operators," and are heavily marketed to by weapons and tactical gear manufacturers and trainers to spend tax dollars on specialized equipment and training.
While some people won't question the LAPD or NYPD getting better gear to protect their respective cities, they do question whether it's really necessary for a small town police department in the middle of Alabama, or a small campus or public transit police department, to be packing assault rifles and MRAP vehicles designed to survive IEDs in Iraq.
MRAP vehicles are hardened against IED blasts (which also makes them bulletproof), and are good for very little else. They are notoriously top-heavy and prone to rollovers, leading to many noncombat injuries of passengers and crew. They also cost a lot of money to operate. In short, they were tailored specifically for the Iraq War, and with that war over, the federal government has been only too happy to sell them cheap to local jurisdictions, thus recovering at least a little bit of the money spent on them. Just how suited they are for police work, or how competent a given police department is in operating these vehicles, is another matter, Concerns about police militarization were heightened when cops started using said gear to carry out routine arrests or serve warrants for relatively small offenses.
This "militarization of the police" has been controversial. Large city police departments that can afford to buy new armored cars for their SWAT teams prefer ones specifically designed for police use like the BearCat, which are immune to any rifle up to and including .50 BMG but are much lighter, safer, lower-maintenance and have larger passenger capacity than military surplus MRAPs. So ironically, the smaller a police department is, the more likely it is to be using a 20-ton military truck.
- Fourth, the current page illustration is probably the most representative visual for what American cops really spend their time doing: reports & paperwork. An early (1970) study in the Journal of Criminal Law & Criminology estimated that up to 50% of the average patrol officer's time was taken with administrative tasks. By the 2010s, a popular textbook, An Introduction to Policing, reported that the percentage had been lowered to approximately 20%, largely due to computerization. Still, numerous online officer forums confirm that one felony arrest probably equals two hours of paperwork, or more.
- Fifth, there are nearly 18,000 different law enforcement agencies of a huge variety of types (see below) operating across the United States, making any attempt to codify what a "typical" agency resembles an exercise in futility - this also leads to wild variations in training, priorities, doctrine, culture etc. between them compounded by the different laws each state has on their books - this can make interactions with law enforcement and the justice system a minefield for the average citizen or visitor. There’s a reason there are around twice as many lawyers as police in the US.
City police forces handle most crimes in their cities. They range in size from the New York City Police Department, by far the largest police force in the US with more than 38,000 sworn officers and another 19,000 civilian employees, down to quite a few that have single-digit forces. Regardless of size, they are headed by a Commissioner, Chief, or Superintendent, who is usually appointed by the Mayor or City Manager, possibly with the approval of the city council or an appointed police commission.
The Sheriff's office or department is the typical name for a county-level local police agency, and handles crimes where people flee between cities, or where the crimes take place in areas not incorporated into a municipality below the county level. In most of these counties, the Sheriff is an elected office. Most of the Sheriff's force are deputies, which are hired positions. Sheriffs or county marshals almost always serve as the primary enforcement arm of the local courts, serving warrants, writs, evictions, and other court orders, and running the local jail system (in many places, these roles may be all that the sheriff is responsible for).
Sheriffs are also commonly designated in many places by law as the county coroner,note often a position called the "Sheriff-Coroner," and has responsibility for finding and properly handling unclaimed dead bodies in the county (and, very often, also running the local medical examiner's office).
Sheriff's offices in large counties with no large city often handle specialized and expensive law enforcement resources, like evidence laboratories, bomb squads, search and rescue teams, or SWAT teams, and make these available to the local police agencies too small to have their own versions of these.
In some cases multiple cities may form metropolitan police departments that merge city- and county-level agencies into a single department with county-wide jurisdiction. The Las Vegas Metropolitan Police Department (LVMPD, or "Metro") is an example, having been created by a merger of the Clark County Sheriff's Office and most of the local police departments in the Vegas metropolitan area (including the former Las Vegas Police Department), with the elected Sheriff of Clark County serving as the head of the department). The Miami-Dade Police Department is another example. Smaller cities may also contract out police services to larger neighbors, including the Sheriff. In rural areas not large enough for their own police force and for crimes taking place on state highways, the state police or highway patrol has jurisdiction.
Of course, this doesn't apply everywhere. In some places the police have completely supplanted the Sheriff as the primary law enforcement officer, in which case the Sheriff may shift into a role similar to the U.S. Marshals (see below) as an enforcement arm of the courts...or they may have had those duties assigned to the Staties or another agency, in which case they don't really serve much of a purpose but continue to stick around anyway. (Everyone in New York City knows about the NYPD, but 9 out of 10 New Yorkers probably don't know that the New York City Sheriff's Office still exists, let alone what they donote .)
In some of America's metro areas, Sheriff's departments are also often given jobs city police forces find too difficult or that don't fall clearly into any one agency's jurisdiction; e.g. the Los Angeles County Sheriff's Department polices Southern California's passenger railways, including the LA subway. Likewise, the San Francisco Sheriff's Department handles law enforcement and security for the civil and criminal courts, City Hall, the Emergency Communications & Dispatch center, San Francisco General Hospital, Laguna Honda Hospital, and several public health clinics, supplementing the San Francisco Police Department.
Since county sheriffs are traditionally elected officials in many states, usually as provided by state constitutions and county charters, maintaining the office may be legally required even if their remaining duties are minimal or mostly ceremonial.
Alternately, in many rural counties, the Sheriff's Department is probably the most powerful local agency. This may be the case because the county has numerous towns too small to justify having their own police department, or one town that does support a police department but also a large county with a significant but widely dispersed population. In such counties, deputies may fulfill most or all of the roles local police are typically responsible for.
Finally, many modern American urban areas are made up of core cities surrounded by sprawling metropolitan areas that may span across significant stretches of a state (or across multiple states), which may have both large city police departments with jurisdiction over the core cities as well as large county sheriff's departments with jurisdiction over the broader metro areas (the Los Angeles metro area is a prime example of this — with a city police department and a county sheriff's department of roughly equal size, along with many smaller local police departments — as are most urban areas in Florida).
Several distinctions typically exist between local and county hierarchies, as well. The sheriff is almost always an elected official, but the police chief may be appointed. Consequently, while the chief can be fired, the sheriff may require a staggering effort to remove from office sooner than the next election. The sheriff may also have far broader powers over his department; many sheriffs can and do set "morality guidelines" regulating everything from facial hair to cohabitation status (yes - a deputy can be legally discharged for shacking up without getting married in some counties), and may be able to fire deputies for any reason or no reason (by technically not firing them, but ending their contract of employment, as the sheriff may be able to deputize and release at his own discretion, without oversight), even if that reason is unbelievably stupid. By contrast, most chiefs are tightly bound by policies and regulations and have significant oversight. As the sheriff may also be responsible for the county jail, the coroner's office, issuance of various licenses and permits, serving warrants, and numerous other tasks, he is sometimes the most powerful public official in the county.
In counties where both agencies have comparable powers and responsibilities, don't be surprised to see inter-department rivalry, sometimes friendly, sometimes less so. Occasionally state departments get thrown into the ecosystem as well, and typically neither local department likes them for it. All law enforcement agencies within a geographic area will, however, normally maintain mutual-aid agreements that call for providing assistance to each other in the event of an emergency, or even just in circumstances where extra manpower may be required (e.g., for crowd control of a large public event).
As far as an example of enforcement goes, the hierarchy for Beverly Hills in California is like this: Beverly Hills, then LA County Sheriff, then California; unless the miscreant flees from Beverly Hills to Malibu via non-county or state roadways. Then it is Beverly Hills, LAPD, California State, then Los Angeles County Sheriff (via contract with Malibu City). State and federal come later, depending on what the miscreant was up to.
To put that in Layman's Terms, if you mess up in Beverly Hills and flee in any direction more than four miles, there will be up to six agencies trying to get an arrest statistic with you as the number.
One factor that has loomed large in the management and policies of many large local police departments since the 1980s is civil rights litigation and resulting direct oversight by the courts. Lawsuits alleging patterns of civil rights violations by police departments, brought by the U.S. Department of Justice's Civil Rights Division as well as by private plaintiffs, have forced many police and sheriff's departments into so-called "consent decrees" under which they agree to adopt specific reforms or institute policies designed to remedy alleged patterns of abusive and illegal conduct. While they're in effect, these decrees put departments under the direct supervision of the issuing courts, with regular and ongoing monitoring by the judge hearing the case (most often a U.S. District Court federal judge, typically through a court-appointed "special master" empowered to oversee compliance with the decree). While police have always ultimately answered to the courts in the course of litigation, civil or criminal, the modern trend has meant that direct management of law enforcement has become a function not only of police brass or local elected officials (or voters), but also directly of the courts as well. Police attitudes about this trend have been mixed, to say the least.
In 2020, all of this is being clouded by the current "Defund the Police" movement ignited by several well-publicized excessive uses of force. Where it will end is of course both too soon and too controversial to tell.
Traditionally, many of these state police agencies were set up along paramilitary lines, especially in the Northeastern United States, and often use military-style uniforms, ranks, and organization (e.g., the use of the title and rank "Trooper," and commonly a "Smokey Bear"-style campaign hat as part of the uniform). They are variously called the State Police, the State Troopers, the State Patrol, the Highway Patrol, or the State Highway Patrol.
The latter nomenclature came about because, in most of the States, they are also (and primarily) responsible for patrol of the highways, including Interstate highways passing through the state, and enforcement of traffic laws thereon. That means they're most commonly known to and encountered by the average citizen for writing tickets for violations of traffic laws, as well as enforcement of auto and trucking safety regulations and inspections. It also means though they usually have the responsibility for managing the response to hazardous conditions that impact the highways, such as automobile accidents, inclement weather conditions, or hazardous materials incidents. (This is a much more difficult and dangerous aspect of police work than most people realize, especially in parts of the U.S. that regularly experience severe weather. Cops don't get snow days off.) Highway patrol duties also mean that state police are typically involved in drug interdiction as well, especially along high-traffic drug corridors.
State police also usually maintain statewide criminal justice, public safety, and investigatory resources that are usable by smaller agencies in their particular state, such as crime labs, search and rescue, air support, and criminal records databases, as well as commonly serving as the default point of contact for federal or other states' agencies involved in investigations across state lines. The State Police can also be called in if there is a conflict of interest with the local police force or accusations of corruption, or to provide extra manpower to local agencies during an emergency.
Most states also have a SBI, State Bureau of Investigations, which is an agency of (mostly) plainclothes officers whose primary duty is, natch, investigative work. These agencies also have a variety of names: (Name of state) Bureau of Investigation or Criminal Investigation Division (CID) are the most common. To make matters even more confusing, in some states these agencies are branches of the same state police as the uniformed patrol officers; in others they are different agencies under a single larger "department of public safety"; and in still other states they are completely separate. (Most states also have separate fish and game agencies intended to protect the state's wildlife and enforce hunting, fishing, and conservation laws.)
A common situation in some smaller states is to give the state police agency primary responsibility for most homicide investigations. For example, the Massachusetts State Police handles all homicides occurring outside of Boston, Springfield, and Worcester (sorry, Jesse Stone). In Maine, the Staties investigate homicides occurring outside of Bangor, Portland, and Cabot Cove.
In fiction, probably the best known examples of state police protagonists are the California Highway Patrol and, of course, the Texas Rangers (technically the Texas Ranger Division of the Texas Department of Public Safety (TxDPS)).
One often overlooked but major type of law enforcement agency that also typically operates at the state level is the corrections department that operates the state's prisons. Obviously, they have jurisdiction over prisons, which have the highest concentration of criminals, but these departments are often also responsible for managing convicted felons on probation or parole, pursuing escapees, fugitives, and parole violators, and investigating criminal activities that are taking place both inside and outside prisons (e.g.: gang and drug activity). This makes these very active and busy agencies, operating often as much outside of prison in the "free world" as inside, and often surprisingly large (the California Department of Corrections and Rehabilitation (CDCR), for example, is actually the second-largest law enforcement agency in the United States after the NYPD).
Or to be short: The original reason for the FBI is that DOJ's lawyers needed people to find information for them to actually convict people who were accused of breaking the law, and things kind of snowballed from there. With only two exceptions though, (and excluding "acting" Directors who served temporarily pending appointment of a new permanent Director), FBI Directors have generally not come from the ranks of FBI agents or from any other law enforcement background, but have instead typically had prior careers as Justice Department lawyers (and, in three cases, prior careers as federal judges). However, traditionally many FBI agents have also been lawyers themselves (the Bureau once required all prospective agents to have training in either law or accounting). In practice, the FBI works very closely with the 93 U.S. Attorney's offices (federal prosecutors) around the country, who typically direct their investigations, pursues search warrants and subpoenas, and authorizes arrests.
The FBI was founded in 1908 and became famous in the 1930s for its battles with bank robbers and kidnappers. Of the latter, the most infamous was probably "Machine Gun" Kelly; his (alleged) cry of "Don't shoot, G-Men!" gave the FBI a nickname that would last for decades. Of the former, "Baby Face" Nelson, "Pretty Boy" Floyd and John Dillinger were by far the most publicized. Almost immediately after the bank robber era ended, World War II engulfed the U.S. The FBI, following the lead set by British Intelligence, completely outclassed the Axis spy agencies; also, while the FBI did arrest German, Italian and Japanese "aliens" in America who were clear dangers to the war effort, the Director of the FBI vehemently opposed the mass internment of Japanese-Americans ordered by the Roosevelt administration.
The latter fact tends to be overlooked in modern discussions of that Director. For nearly 50 years the FBI was headed by J. Edgar Hoover, who blurred the line between brilliant law-enforcement administrator and paranoid tyrant. When he joined the Bureau of Investigation, predecessor to the FBI, it was a practically powerless nonentity rife with corruption; from 1935 through the 1970s, he made it synonymous (to the vast majority of Americans) with effective, efficient and incorruptible law enforcement. He also made himself synonymous with the agency. After his death, some of the luster was peeled away; it was revealed that, without particular regard for Constitutional niceties, he tapped phones and assembled files on...well, we can't really be sure about how many people he was spying on, since the files were all destroyed after his death.note No Director since has achieved his level of fame, though the Bureau has slowly reclaimed much of its previous good reputation.
Perhaps influenced by Hoover, the FBI has long been associated with a muted, stern, conservative internal culture and public image. In his day, Hoover refused to allow the FBI to participate in most sorts of undercover assignments, believing it was an avenue to corruption, and was usually more interested in hunting suspected Communists or other perceived subversives than traditional criminals. An old joke holds that "going undercover" for an FBI agent means taking off his coat and tie. To this day, "Donnie Brasco"-style FBI undercover operations are still rare (it's difficult to keep a clean enough personal history to get hired by the FBI and then be able to pass convincingly as a criminal). As a result, the FBI has always been better able to make cases based on informants, subpoenas, scientific investigation, and surveillance than it has been through any kind of undercover work.
The FBI is automatically called in if a crime crosses state lines, or in special cases for crimes that do not but that fall under federal jurisdiction for one reason or another. There are currently at least 5,000 specific federal offenses, so an exact enumeration of what might bring in the FBI is beyond the scope of this article or, indeed, all the combined contributors to this wiki. However, some general guidelines, important specifics, and interesting cases can be noted:
- A federal crime typically involves something that crosses state lines or involves multiple states or interstate commerce, or one that interferes directly with the federal government's business—assaulting a federal employee in official business, crimes on federal property, destruction of mailboxes... what? You read that right, that's a federal matter (mailboxes deal with the mail, which is handled by the US Postal Service, which is a federal government corporation created by Congress' power under Article I, Section 8, Clause 7 of the Constitution to create a post office). Good luck actually getting the FBI to come investigate someone messing with your mail, but legally it is their problem.
- Although they do investigate serial mailbox destruction as it is a sign of tampering with the mail and, also, crimes like identity theft and destruction of evidence.
- And speaking of mailboxes, most people don't realize that the Post Office has its own police force (See "Other police forces," below) so chances are, they handle it first before passing it on to the FBI.
- As is the case with all federal law enforcement since September 11, 2001, counterterrorism and national security matters in general are a major part of the FBI's caseload and are treated as a top priority (enough so that there have been accusations that its work pursuing more ordinary criminal matters has been neglected).
- The FBI also may be called in to investigate local and State police if there is a conflict of interest or accusations of corruption. National law gives them the power to investigate if anyone's "Civil Rights" are violated. Since one of the rights is the right to a fair trial, this automatically covers corruption or brutality.
- The FBI directly administers the national-level databases that maintain law enforcement records for the entire country, including criminal and arrest records, fingerprint records, missing and unidentified persons, records of stolen property, files on wanted felons and fugitives, known gang affiliates, suspected terrorists, sex offenders, and a large variety of other records relevant to law enforcement nationwide (as well as to law enforcement in other countries). The division of the FBI that does this, Criminal Justice Information Services (CJIS), is actually the largest division of the Bureau. At the other end of every computer in every police car and station in America is, ultimately, the FBI and its records.
- The FBI also manages many other national level intelligence, forensic and other specialized investigative activities, such as crime laboratories, intelligence analysis "fusion centers," cyber investigations, translators, and the like. Much of this work is conducted by FBI Intelligence Analysts (OPM Occupational Series 1805) who are distinct from the FBI's Special Agents (the general official title for most federal law enforcement officers, OPM Occupational Series 1811, Criminal Investigator).
- Since copyright falls under federal law, the FBI puts warnings that they will raid copyright infringers and slap them with heavy fines and prison sentences on every videotape and DVD sold in America. How much they actually do this depends upon the entertainment industry's generous, er, campaign contributions to members of Congress this term, and, also, the scale of the violation— basically, if you make a business out of counterfeiting Blu-Rays, sooner or later the G-Men will show up.
- As noted above, the FBI made its rep battling bank robbers and kidnappers like John Dillinger and Baby Face Nelson. The quantum leap forward in automotive technology in the late 20s and early 30s allowed criminals to rob or kidnap in one state and avoid prosecution by simply hotfooting it across a state line; in Bonnie and Clyde, Clyde references this directly. To combat this, Congress passed the Federal Kidnapping Act of 1932 (in response to the infamous Lindbergh kidnapping), and the first of several federal laws against bank robbery in 1934 (most U.S. banks are federally-insured). Now the FBI is automatically called in in such cases.
- In general the FBI's jurisdiction often has it going after the "big fish" - Mafia families and the like. They usually don't bother with the small fry, leaving the local police to handle them, which is just as well, since they don't have jurisdiction anyway. The FBI is however heavily reliant on local police departments for knowledge of their own jurisdictions and often manpower. The Bureau typically has more money and resources than it has people in a particular city or townnote , which means that, usually, both the FBI and local police have an incentive to work together where they can.
- Recognizing this, back to the days of J. Edgar Hoover, the FBI has usually gone out of its way to highlight the work of local law enforcement in contributing to multi-agency investigations, rather than to take the lion's share of credit itself. (In any press conference involving the FBI and local cops, you can usually expect local uniformed police brass to take the lead, while some FBI SAC or ASAC from the local field office in a muted suit or FBI windbreaker will usually only get a few words in afterwards. By contrast, most U.S. Attorney's offices are often eager to claim credit for arrests and prosecutions.)
- In modern practice, much of the local and regional law enforcement work of the FBI (and most other federal law enforcement) is accomplished through coordination with multiple federal, state, and local agencies in various joint "task forces" (e.g., Joint Terrorism Task Forces, Violent Gang Task Forces, cyber task forces, drug task forces, intelligence-sharing fusion centers, and so on) in which the feds contribute federal resources and authority while the local cops are deputized as federal "task force officers." In some cases, this has led to local controversy in certain enforcement areas (such as immigration or terrorism-related investigations). note
- The FBI additionally acts as a de facto clearinghouse for national law enforcement coordination, information sharing, training, and promoting perceived best policies and practices. It conducts various classes and training programs every year for state and local law enforcement, shares intelligence, conducts and publishes research (in coordination with other elements of the Department of Justice), and serves as a liaison and point of coordination for inter-agency coordination across states lines and international borders.
- Unlike in fiction the FBI (and other federal law enforcement agencies) normally cannot unilaterally "take over" a case from state or local law enforcement and direct their operations or prevent them from investigating unless there are extremely unusual circumstances. State and local agencies are created and operate under the law of the states they're located in, which means that under American federalism, they're not subordinate to or under the control of the federal government, and they are not normally obligated to cooperate with the FBI or other federal law enforcement absent a court order or some other particular circumstance. note This provides an additional incentive to the FBI to elicit the cooperation of state and local law enforcement whenever possible.
- A little known fact is that the FBI has jurisdiction over US diplomatic facilities, as they are considered to be part of the United States. The FBI has over 50 overseas offices situated in various US embassies and consulates. They are also responsible for investigating attacks on any of these facilities.
- There are quite a few people (including Americans) who tend to conflate the FBI with the CIA, since they're both major federal goverment bodies that are supposed to stop "bad guys", can cause govermental paranoia, and have three letter acronyms. The CIA doesn't deal with crime at all, however; they spy on foreign nations instead. The FBI does have responsibility over counterintelligence, catching foreign spies in the US, but they don't have any James Bond-types to do it with. The FBI does however pursue investigations of terrorists, spies, and other matters with an international dimension, which does mean that FBI agents can and do wind up working overseas pursuing such people, usually with the cooperation of the State Department, US Military, and their foreign counterparts. In 2005, in the wake of 9/11, the FBI's domestic counterintelligence, counterterrorism, and various other "national security"-related work (e.g., combating weapons of mass destruction) were centralized into the "National Security Branch" (NSB). While technically still part of the FBI, and answerable to the Attorney General, NSB is also considered part of the U.S. Intelligence Community, and accordingly it is also overseen by the Director of National Intelligence.
See FBI Agent for a listing of the extensive uses in fiction.
For more information, and a list of fictional uses, see U.S. Marshal.
Who gets Secret Service protection is controlled by Congress. In addition to the US officials named above, the Service also guards heads of state from other countries when they visit the United States. Former Presidents and their spouses receive protection for the remainder of their lives note —although they can voluntarily surrender such; Richard Nixon was the first to do so — and children of former Presidents receive it until they are 16 years old. Major Presidential candidates can get it fairly early on in the US primary process. There are no hard rules for when candidates are given protection; the metric is a very fuzzy "how good are their chances of winning the election and how many cranks have started threatening them". Barack Obama held the record for being granted Secret Service protection the earliest of any Democrat candidate for President with no prior protection note , while Ben Carson and Donald Trump currently co-hold the record for Republicans.
While the plainclothes agents are, ironically, the most familiar to the public, the Secret Service also provides guards to protect the White House. They wear uniforms and carry firearms the same as any other police officer, have patrol cars for traveling near the White House, and are known as the "Secret Service, Uniformed Division." These guys also travel along with the President providing additional security and firepower as part of a "Counter-Assault Team," basically a SWAT team that exists to fight off an organized, armed attack on the President.
The USSS has the best rate of capturing criminals of any American law-enforcement organization. Due to the nature of counterfeiting, it is a crime for losers (your odds of being caught if you decide to do it in a big way are over 90%), unless you are an actual enemy nation. (Germany started counterfeiting the dollar in WWII after they had their fill of fake pound notes. Modern-day counterfeiters include Iran and North Korea.) They have, by law, access to the cooperation of any and every other part of the Federal government, including the military, in fulfilling their protective duties.
Started out in the Treasury Department (hence references to Ness & co as "T-Men" in stories, or at least in Crossword Puzzles), but currently under DOJ, after having shifted back and forth between these two Executive departments over the 20th century. (Somehow "J-Men" hasn't really caught on.)
The ATF has been a highly controversial agency, in part for its role in the middle of American Gun Politics, as well as several colossal blunders over the years (including their involvement in the Ruby Ridge and Waco sieges in the 1990s, as well as, more recently, the Operation "Fast and Furious" gunrunning scandal). Cynical observers of US politics have observed however that keeping the agency around, in a weakened and discredited state, has been more politically useful to gun rights proponents, such as the NRA, than seriously reforming the agency or abolishing it and giving its duties to another agency, like the FBI.
The areas it's responsible for are listed in the order they were given to the Bureau. Responsibility over explosives was delegated to ATF in 1970, but "Explosives" wasn't added to the agency's title until after 9/11. They slapped it on the end and passed on the golden opportunity to become The Bureau of FATE. Other US law enforcement agencies have not been so stuffy; see "Immigration" below.
ATF is the principal agency that administers federal gun laws, including licensing and regulation of gun dealers and manufacturers, the National Firearms Act (which regulates certain categories of firearms and related equipment like machine guns, short-barreled rifles and shotguns, and silencers), and the paperwork and enforcement on background checks of gun purchasers (though it's the FBI that actually conducts the background checks, as the agency that directly operates the federal government's national criminal records databases). This is the area in which the average citizen is most likely to cross paths with ATF (or at least its paperwork). ATF's operations are divided between this regulatory function, called Industry Operations and conducted by Industry Operations Investigators (IOIs), and criminal investigations carried out by ATF Special Agents.
Responsibility over gun laws tends to regularly involve ATF Special Agents in investigations targeted on violent organized and/or career criminals. Possession of guns or ammunition by anyone who has a prior felony conviction or who is involved in certain types of ongoing criminal activity (drug crimes, in particular) is a serious crime in and of itself (and one that is usually very easy to prove). This makes gun charges an easy way for prosecutors to make cases against such miscreants.
The majority of ATF's work on alcohol and tobacco involves investigating smuggling and diversion of those products in attempts to evade taxes.
Due to its jurisdiction over explosives, ATF is also considered to have the best forensic laboratory resources in the country for investigation of explosions and suspected arson, and so often gets called in on such cases. ATF's explosives expertise was instrumental in tracing the vehicle used in the 1993 World Trade Center bombing. ATF also administers the National Integrated Ballistic Identification Network (NIBIN), which stores digitized recovered ballistic evidence for comparison to suspected crime guns.
In fiction, the ATF is also Steve Jinks's original agency on Warehouse 13.
In fiction, the DEA has never achieved the fame of the FBI although it has fared somewhat better than the ATF. Its most notable appearance is probably in Breaking Bad, which featured a DEA agent, Walter White's brother-in-law Hank Schrader, as something of a Hero Antagonist as Walt built up his meth empire. If they are portrayed in an antagonistic light, then they are more often than not Naughty Narcs. A good example of this trope is The Professional which depicts its main villain Norman Stansfield and his crew as members of the DEA who are otherwise corrupt and have ties to organized crime.
Remember—it's the Drug Enforcement ADMINISTRATION, not the Drug Enforcement Agency. Even journalists get that one wrong.
ICE is the second-largest criminal investigative agency of the federal government (after the FBI), and the largest within the Department of Homeland Security. In practical terms, ICE is actually two separate agencies (law enforcement "directorates," in bureaucratic language). Enforcement and Removal Operations (ERO) handles immigration-related enforcement, and is descended from the portions of the former INS that ICE absorbed. Homeland Security Investigations (HSI) is mostly descended from portions of the U.S. Customs Service, and handles everything else ICE investigates, mostly collateral national security, anti-terrorism, and other investigation work related to customs and immigration. Due to its role in immigration law enforcement, ICE has increasingly faced calls for its abolition by supporters of lenient immigration policy.
The Border Patrol is actually part of Customs and Border Protection (CBP), an agency that's separate from ICE because they have slightly different missions; CBP works mainly at the border and at border crossings. They are also charged with preventing illegal things from crossing the border whereas ICE is responsible for dealing with contraband and illegal entrants after they have crossed.
While it's unusual for most law-abiding people to encounter federal law enforcement on a regular basis, due to their specific missions, ICE and CBP are the ones the average person is probably most likely to ever run across in person, either at or near a U.S. port of entry or else conducting internal immigration enforcement. Controversially, courts have upheld a "border search exception" to the probable cause and warrant requirements of the Fourth Amendment (prohibiting unreasonable searches and seizures). This has been interpreted to give ICE and CBP enhanced authority to operate within 100 miles of any "external boundary of the United States." Given that this area includes everything within 100 miles of a coastline or border, that means most major American cities and nearly two-thirds of the U.S. population are within this zone.note
On top of ICE and CBP, yet a third agency, U.S. Citizenship and Immigration Services (USCIS), was set up to handle the legal immigration and naturalization system when Homeland Security was formed. (If nothing else, 9/11 was a bonanza for federal bureaucracy.) USCIS is responsible for handling and adjudicating applications for and issuance of all immigrant and non-immigrant visas, applications for refugee and asylum status, applications for permanent residence ("green cards"), and the naturalization process (acquisition of U.S. citizenship). The U.S.'s immigration court system, however, is run by the Executive Office for Immigration Review (EOIR), which is part of the Department of Justice.
US law states that anything between the coast and 3 nautical miles (5.6 km) outnote is state territory, while beyond that out to international waters is federal territory.
Coast Guardsmen also serve on Navy and Marine ships in LEDETs (Law Enforcement DETatchments) to handle any civilian-type boardings and such. The Navy and Marines both act as if subject to Posse Comitatusnote , while the CG is not and does not. Port Security Units are also deployed just about everywhere as, well, Port Security.
The main role in terms of law enforcement is in the field of riot control. The Posse Comitatus Act of 1878 note prohibits the use of the regular military in domestic law enforcement (except for when ordered by the President under exceptional circumstances, such as the Insurrection Act, or by a specific act of Congress), but does allow the National Guard to be used. The Guard's other main role has nothing to do with law enforcement at all — they're typically called out for disaster relief operations when a state gets hit by something really nasty.
The National Guard is run by the individual states and is under the authority of the Governor of each state. The President can, however, "federalize" a state National Guard, placing them under his or her control. The most notable case (other than wartime mobilizations) was in 1957, where Arkansas National Guard troopers were taken into federal command by President Dwight D. Eisenhower to enforce racial desegregation in Little Rock schools.
While the National Guard are not police forces, they do have an additional law enforcement implication. It's very common for cops to join the National Guard as a side job, meaning that when a National Guard unit is deployed overseas it can cause significant manpower shortages in police and sheriff's departments, especially for smaller departments in rural areas.
NCIS is a primarily civilian agency that reports directly to the Secretary of the Navy, who is a civilian appointed by the President working directly for the Secretary of Defense, and is thus above/outside both the Navy and Marine Corps service chains of command. However, NCIS works closely with Marine Corps and Navy personnel serving as military police and naval security forces, as well as with other civilian police officers who serve as law enforcement officers at some naval installations. Obviously, due to its relationship with the naval service, it frequently operates abroad as well, often performing investigations and security evaluations of foreign ports that US ships might call to. They conduct criminal investigations under the provisions of the Uniform Code of Military Justice (UCMJ) and other federal statutes. Analogous to the Law & Order TV-series: NCIS is the "Law" part, while JAG is the "Order" part.
It should be noted that the Air Force has the Office of Special Investigations (OSI), the Army has the Criminal Investigation Command (CID), and the DOD Inspector General has the Defense Criminal investigative service (DCIS), all of which serve similar but not identical roles. The Coast Guard has the Coast Guard Investigative Service (CGIS), which is largely similar but since the Coast Guard is itself partially a law enforcement agency this also overlaps with Internal Affairs. None of the others has their own television shows on CBS, however.
- For those wondering why a military branch needs a civilian agency for criminal investigation, there are three reasons:
- One, since they work with the service but are not part of the military chain of command, it gives them a certain flexibility when dealing with military personnel as they don't have to play as many games with rank.
- Two, the Director and Special Agents don't depend on military officers for promotions and future assignments. This is pretty much the reason why NIS was reorganized into NCIS in 1992, following the botched Tailhook investigations.
- Three, civilian control of the military is a part of government with both deep historical roots and very strong bipartisan support in the US, but equally strong is the respect for military professionalism and the recognition of the military as a unique separate society. A specialized civilian agency is the tradeoff solution.
- The US Army force is the M.P.s, short for Military Police.
- The US Navy police is the M.A.s, short for Master-at-Arms.
- The US Air Force law enforcement branch is the S.F.s, short for Security Forces (not Special Forces).
- The US Coast Guard has M.E.s, which is short for Maritime Enforcement specialists.
- The US Marine Corps also has M.P.s. Since the Marine Corps is also part of the Navy Department and gets embarked at Sea, Navy Masters-at-Arms may find themselves dealing with miscreant Marines as well.
In garrison, all branches are primarily concerned with crimes committed on base, and with providing security to military assets and facilities. A lot of their work involves the same things as civilian police, albeit with the additional requirement of being the last resort for enforcing military discipline among the ranks. On base, M.P.s patrol the streets, write speeding tickets, bust servicemembers for DUI, investigate domestic disturbance callsnote and sexual assaults,note and the like. In any given military movie, expect them to show up to bring any zany (or drunken) hijinks to an end when The Squad sneaks out for a night to unwind. Equipment, training, specific roles, and tactics vary from one service to the next (the Army Military Police and the Air Force Security Forces have differing standard procedures for firearms handling, much to the ongoing chagrin and amusement of either branch).
Jurisdiction Friction is generally avoided: The MPs deal with stuff on base, the local police handle everything off base. (Though on military bases overseas, the situation can get very difficult when U.S. troops are accused of crimes by local authorities.) Any Hot Pursuit situation on the base can be contained by closing the (very sturdy) gates, and any Hot Pursuit situation leading onto the base... is generally not a recommended course of action. Assuming that the aforementioned gate isn't quickly blocked off (and it almost always can be, very quickly), the military cops are armed and do not take kindly to unauthorized personnel trying to force their way onto the base, due to previous incidents involving vehicle bombs. The U.S. military, including M.P.s, is largely restricted by the Posse Comitatus Act and the Insurrection Act of 1807 from being used for civilian law enforcement within the United States in most circumstances. In the event of on-base crimes that aren't an open and shut case, the MPs will call in their respective service's criminal investigative service to collect evidence and interview witnesses, just like how beat cops would call in the appropriate detectives in a civilian police force.
Until shortly after 9/11, the Navy did not have much of a security force. The MA rating was all senior enlisted, and they were more concerned with keeping order aboard ship. A carrier with several thousand people needs a police force. Base Security was mostly civilian police, with a few MA's on shore duty. Since then, they've expanded into a large military police and security force. As well as standard service police, alongside Marines they protect the Navy's portion of Peace Through Superior Firepower. Also, sailors can be assigned to the Shore Patrol, a kind of auxiliary police that's more concerned with ensuring Sailors and Marines out on the town don't cause too much trouble. And that they come back to their ship when shore leave is over, rather than going AWOL for some extra partying.
When military forces are deployed, M.P.s often wind up in a quasi-police, quasi-combat, quasi-civil affairs role. They still have to maintain discipline and uphold the law among the deployed forces, but they also have to support the overall military effort in various ways, including traffic control of tactical vehicles, security, anti-terrorism, working dog handling, prisoner handling, vessel boarding, search and seizure, and the like.
Post 9/11, this role became extremely significant, especially in Iraq and Afghanistan, where Coalition military forces essentially had to take over all of the normal roles of domestic government post-invasion. The fact that the entire U.S. military in 2003 didn't have enough qualified, trained, active duty M.P.s to assume the entirety of police and security functions for two foreign countries with active insurgency movements became a serious problem. The military tried to resolve it by hastily mobilizing reservists who were off-duty cops or prison guards, retraining other soldiers as "provisional M.P.s," and cramming marginal recruits into M.P. units. It is probably not a coincidence that, within the next couple years, the U.S. found itself embroiled in several nasty scandals over prisoner abuse, such as at Abu Ghraib in Iraq and Bagram in Afghanistan.
For the most part, if you don't work on a military base, you'll never encounter the MPs. There is a separate civilian police force guarding The Pentagon, the Pentagon Force Protection Agency (PFPA), which pretty much does the same things there as the various military polices forces does elsewhere. Many military installations will also hire civilian police officers or security to work alongside the uniformed policemen, though you're less likely to see one of these civilian cops in a military movie.
After 9/11, the FAMS was massively expanded and moved into the newly created TSA. They carry concealed weapons and sit on board regular flights while posing as normal passengers. Unlike most branches of law enforcement, they act preemptively. Air Marshals go where no crime has been committed, so that they will be in place to respond should anything (like, oh let's say, 3 or 4 men with box cutters attempting to take control of the plane) occur.
One large yet relatively unknown example is the United States Postal Inspection Service, which investigates mail fraud, protects postal facilities in high crime areas, and protects sensitive mail deliveriesnote . Any time that criminal activity involves or uses the U.S. mail (which is quite often), it automatically becomes a federal crime (usually mail fraud, 18 U.S.C. § 1341) even if the underlying crime wasn't, and these folks will become involved. Of note, they're also the oldest law enforcement organization in the U.S., predating the founding of the nation by a few years.
The overabundance of police agencies, as you might expect, leads to some jurisdictional absurdity; the corner of First Street and East Capitol in DC sits between three government buildings (the Capitol, the Supreme Court, and the Library of Congress), each of which has its own police force separate from the DC Metropolitan Police, who patrol the intersection itself. It also leads to other interesting questions; the 2010 purchase of short-barreled shotguns by the Department of Education (for their fraud investigators) has sparked reactions ranging from humorous to possibly paranoid.
At the state and local level, there can be many "special duty" or "special district" law enforcement agencies with varying responsibilities, including transit police, port police, airport police, school district police, note housing authority police, note and on and on.note Other agencies often have personnel with law enforcement powers (i.e., to go armed and make arrests) incidental to their duties, such as fire marshals, note gaming officials, note park rangers, note fish and game wardens, note or alcoholic beverage control officers. note Additionally, in many states, any state or local prosecutor's office over a certain size will often maintain their own internal bureau of investigators, generally recruited from experienced police detectives, to assist with ongoing prosecutions or to conduct specialized, targeted investigations directed by the prosecutors. note Also, although they're not generally thought of as law enforcement in the traditional sense, government regulatory agencies at every level (from local building permitting agencies all the way up to federal agencies overseeing complex international industries) have the authority to conduct investigations, inspections, and to make binding administrative determinations of matters within their jurisdiction. Those powers can be and are enforced when necessary by courts and cops, and willful violations of many of the regulations they issue and oversee can constitute criminal offenses in many jurisdictions.
Some non-governmental entities have also been given authority to establish forces on their properties with full police power — including, of course, the legal right to carry and use firearms. An unusual example is America's railroads. The decline of rail in most of the US as a means of individual travel is probably why no major works of fiction deal with railroad police, but they are trained and sworn law enforcement officers with both state and (limited) federal authority.
Much more commonly encountered are the police forces authorized to universities. Campus cops also rarely appear in fiction unless it's as the butt of a joke, but you have to learn the trade somewhere. Still, in some big university systems, campus police are a force to be reckoned with. For example, the University of California system's force covers all 11 UC campuses, and the California State University system's officers are responsible for all 24 schools. In addition, due to the fact that most public universities in the US are technically State land, campus police forces at many state universities are drawn from the State Highway Patrol and have the training that one would expect for State police. note It should also be noted that many private universities have their own police departments of fully-sworn officers, as well.
Given the fact that college and university campuses are large public spaces with thousands of students, faculty, and visitors in attendance, and can all too often be the site of things such as unruly sports mobs, violent protests, active shooters, or terrorist incidents, as well as drunken frat-bros, many campus police departments maintain qualifications in operations such as crowd and riot control, SWAT, and bomb disposal, as well as close cooperative relationships with other local police agencies in emergencies. The Hyde Park neighborhood of Chicago, where former President Barack Obama maintains a home, is widely regarded as one of the safest neighborhoods on the traditionally crime-ridden South Side of Chicago, due in part to the fact that the University of Chicago located there has its own police department which patrols the neighborhood alongside the Chicago Police Department.
Despite all this, the distinction between "campus security" and "campus police" is sometimes lost on new students...until they drunkenly assume they don't have to listen to a "rent-a-cop." Hilarity Ensues.
As the day-to-day work of such a limited police force will probably not be matters of life and death, if they show up in fiction, it'll probably be to get in the way. Of course, the day-to-day work of most police officers isn't life or death either, so there may be room for creative exploration here.
Although most larger well funded police departments have IA divisions, large scale corruption cases can sometimes only be investigated by State Police, or in some egregious cases, the FBI. When systematic civil rights violations are involved, such as what is alleged to have happened in Ferguson, Missouri, the IA work is done by the Federal Department of Justice's Civil Rights Division. This division can go after policemen who have been cleared of wrongdoing by state or local IA divisions, because civil rights violations are a federal matter.
At the federal level, the FBI, ATF, DEA etc are "policed" by the Department of Justice's Office of Professional Responsibility (OPR). Unlike state or local police IA divisions, where an IA cop is still a cop, federal law enforcement do not police their own. Rather, it is the prosecution service that polices them. Also, as noted above, nearly every federal executive department and agency (including the Justice, Homeland Security, and Treasury Departments) has an Office of the Inspector General (OIG), whose mission is to investigate and prevent fraud, waste, abuse, and malfeasance of all types within the various agencies and departments.