A lot of cops in media have a history in the military. Maybe they're a former Marine, or a soldier in the Army Reserves. You don't usually see a cop who was in the Air Force, Coast Guard or the Navy (excluding Navy SEALs). This trope is very much Truth in Television since police departments routinely recruit from the military because of the overlap in training at a police academy and military basic training.
Basically, this trope applies to all members of law enforcement who've done a stint in the military, including the Reserves and National Guard. Note: this trope is not specific to only America, other countries' militaries also count.
Contrast with From Camouflage to Criminal, when outlaws have an ex-military background.
Some examples separated by service branch:
- V for Vendetta has an "Intermission", "Vertigo", where a "Fingerman" for the Norsefire government puts a man walking on the outside of a building as a sick form of interrogation (despite being sure he doesn't really know anything about V, he's just personally in a bad mood). V saves the man and puts the Fingerman, name of Colin, through the same routine under threat of certain death at his hands. The narration puts the reader into the head of Colin Clarke, a veteran Fingerman, a soldier before that who had to cope with worse than this in his training courses. Whoever trained Colin never put a Banana Peel in the way.
- As part of his re-imagining in Batman: Year One, Jim Gordon is an Army veteran. As is Detective Flass, who was in special forces. Gordon muses it had been some time before he'd kicked a Green Beret's ass.
- Thomas "Tiger Tank" Nightingale from Rivers of London did see military action during World War II before settling down to a specialist position in The Met, but it's unclear under which branch he (and the rest of the Folly) served.
- Foyle's War - Foyle is a veteran of World War I. His sidekick, Sergeant Milner, starts the series in active service, but returns to police work after being losing a leg.
- Hawaii Five-0 (2010 remake) - Steve McGarrett's father, John was a retired cop and Vietnam vet.
- The Kill Point: Lieutenant Connie Reubens, the SWAT team leader, has done tours in Afghanistan. She says it really pisses her off that the hostage takers are attempting to use their own service background to invoke public support.
- Resident Evil: In early background materials related to the first game, Jill Valentine was stated to have been from Delta Force, which is U.S. Army. However, as the franchise has grown, this aspect of her character was dropped, and current materials simply state she has a special forces background with no further details given.
Anime and Manga
- Ghost in the Shell - Most of Section 9 (except Pazu, Togusa and Saito) had served in the JGSDF prior to the unit's formation.
Films (Live Action)
- Shutter Island: Teddy Daniels is a US Marshal and was a soldier during the Dachau liberation reprisals.
- The Punisher (2004): Before he starts doing his thing, Frank Castle was an FBI agent, and years before that, a Delta operator in the Gulf war.
- Gangster Squad: O'Mara, Wooters, and Keeler are WWII veterans. O'Mara leads the titular unit, and is a WWII veteran with a classified record, and is implied to have been as OSS commando, while Keeler was in intelligence. Wooters was a Navy aviator.
- The Andy Griffith Show - Both Andy Taylor and Barney Fife served in World War II, however neither saw combat, and Barney admits that he was not allowed to leave the States.
- In APB, Officer Nicholas Brandt mentions in "Risky Business" that he used to be in the military. "Pandora's Box" mentions that he was an ex-Ranger.
- The Border - Mike Kessler was with the Canadian Army and served in Joint Task Force 2 during peacekeeping in the Balkans.
- Bones - Seeley Booth (Ranger)
- The Bridge - Inverted and then played straight in one episode. A police officer took leave from work and joined the army so he could serve in Afghanistan. He was wounded and had his foot amputated. When he returns he tries to become a police officer again despite his disability. Frank and the police union end up supporting him after he proves that he is still capable of doing the job even with a prosthetic foot.
- Colonel March of Scotland Yard: In "The Headless Hat", March mentions that he was in Army Intelligence during WWII, which taught him a few tricks of his own. It is not known if he was a police officer before the war and joined up for the duration, or if he joined the police after leaving the army.
- Crisis (2017) - Akira Inami used to be with the Japanese Ground Self-Defense Force's Special Forces Group.
- Dexter - James Doakes (Ranger)
- Dragnet - Bill Gannon and Joe Friday
- The FBI - Inspector Lew Erskine was a captain in the US Army during The Korean War.
- Flashpoint - Sam Braddock (Canadian Army, specifically with Joint Task Force 2.)
- Forbrydelsen - Ulrik Strange, Lund's new partner in the second season, was in the Danish Army. He was a Sociopathic Soldier who commits the murders of the season to cover up the war crimes he committed.
- Gang Related - Ryan Lopez used to be with the 75th Ranger Regiment before he joined with the LAPD.
- Gotham - Jim Gordon had served in the US Army prior to returning to Gotham.
- Hill Street Blues had SWAT Team commander Howard Hunter, who Captain Furillo regularly had to restrain from applying the tactics he used in Vietnam to policing Hill District, and rather more down-to-earth beat cop Joe Coffee. Chief Daniels also once mentions he served in The Korean War.
- Happy Days - Officer Kirk
- Justified - Deputy US Marshall Tim Gutterson was a sniper with the US Army Rangers
- The Meeting Place Cannot Be Changed - Vladimir Sharapov was a former Red Army scout, now in Moscow Criminal Police.
- NCIS - Downplayed as he's not actually an agent, but Chief Medical Inspector Donald "Ducky" Mallard started his medical career in the UK's Royal Army Medical Corp
- Nichols - Frank Nichols served for 18 years in the US Army Cavalry before becoming sick of killing and returning to his hometown where he is made sheriff against his will. Something of a subversion because he is a Technical Pacifist who refuses to carry a gun.
- NUMB3RS- Colby Granger was an Army CID investigator before joining the FBI. It was during this time he was pinned after an explosion, from which Dwayne Carter saved his life.
- Person of Interest:
- Detective Jocelyn "Joss" Carter served in the United States Army as a Warrant Officer, first at Bagram Air Base in Afghanistan from February 2, 2002 until February 2, 2003. She was then relocated to Camp Liberty in Baghdad from January 20, 2003 until March 20, 2004 when she received a Purple Heart, serving as an Army Human Intelligence Collector and top interrogator.
- Reese was a Ranger and Green Beret before being recruited by the CIA. After leaving the CIA, he was eventually given a cover identity as a NYPD detective.
- True Detective - Paul Woodrugh used to serve in the US Army prior to being a contractor with Black Mountain. He resigned after BM got involved in scandals, joining the California Highway Patrol.
- Harry Bosch, the LAPD homicide cop who is the central character in about 3/4 of Michael Connelly's mystery novels, was an Army "tunnel rat" in Vietnam, fighting the NVA in underground tunnels. Bosch's Vietnam experience is key to the plot of debut novel The Black Echo, in which he discovers the corpse of a fellow tunnel rat, and is referred to often in subsequent books. In the TV adaptation, he served in the First Gulf War and in Afghanistan.
- In the 87th Precinct novels, Steve Carella and Bert Kling both served in the army before joining the police. Originally Steve served in World War II and Bert in The Korean War. In later novels Comic-Book Time, just made vague references to 'the war', with the constant being that Bert's service is more recent than Steve's.
- Booker DeWitt was in the 7th Cavalry and became a private investigator afterwards.
- In Dragon Age II, Aveline Vallen is introduced as a survivor of the battle of Ostagar, where she was an officer in the Ferelden army. Throughout the game, she joins the City Guard of Kirkwall and goes up the ranks, becoming their commander.
- Left Alive has Olga Sergeevna Kalinina, formerly with the Garmoniyan Army as a veteran wanzer pilot who left service and worked in Novo Slava as a uniformed officer after her daughter is killed.
- Barney Miller - Wojo is a Marine and a Vietnam vet.
- Blue Bloods - this show is made of this trope: Henry Reagan was in Korea, his son Frank was in Vietnam, and Frank's son Danny served in the second Iraq War. Plus it's also mentioned that Henry's father was in Normandy on D-Day and knowing this family, was almost certainly also a cop.
- Criminal Minds - David Rossi
- CSI - Jim Brass
- CSI: NY - Mac Taylor
- LA Confidential - Ed Exley is a former Marine who served in the Pacific during World War II.
- Law & Order: Special Victims Unit - Elliot Stabler was a Marine veteran of the Gulf War. Even when not directly mentioned, his Marine Corps status is referenced by the Eagle, Globe and Anchor tattoo on his right forearm.
- Longmire - Walt Longmire, specifically as an MP in Vietnam.
- NYPD Blue:
- Detective Andy Sipowicz is a former Marine and a Vietnam veteran. Do not lie about serving in Vietnam in front of him.
- His son Andy Jr. joins the Air Force; after he is discharged due to an injury he applies for and is accepted into Hackensack NJ's police force training program.
- Andy's third partner Danny Sorensen is a former Special Forces ranger.
- NCIS - Gibbs. He was a Marine Corps Gunnery Sergeant and Scout Sniper who served in the invasion of Panama and the First Gulf War. Likewise his mentor Mike Franks was a Marine before becoming an NCIS agent.
- Quantico - FBI Agent Ryan Booth is a former Marine with service in Iraq and Afghanistan and a Bronze Star recipient.
- Luke Cage (2016) - Before Luke was framed and sent to prison, he was a cop, and before that, a Marine in Force Recon. His father had talked a judge into allowing him to enlist instead of going into juvie after some youthful indiscretion (he and a friend stole a car for fun).
- Dexter - Albert Doakes
- In near-future thriller Victoria, most of the early Christian Marines subversives and militiamen are military veterans presently employed as law enforcement officers in some capacity or other. Naturally, this also later aids their infiltration of the police forces.
- L.A. Noire - Cole Phelps was a Marine in WWII. His past and that of the rest of his former unit plays a major role in the plot.
- Mass Effect has Maeko Matsuo, captain of the Elanus Risk Control Services private police force on Noveria and an ex-Alliance marine.
- NYPD Blue creative consultant Bill Clark is a former NYPD detective and served in the Army and later the Army reserves, attaining the rank of Major.
- In Arise, Bato was a JMSDF commander before joining the Section 9, ironically outranking Motoko for a full grade.
- Fatherland - German police officer Xavier March and reluctant SS police major is also, or has been, a Kapitan zur See in the Kriegsmarine - one of Doenitz's U-Boat commanders. Also applies to the book.
- Tag Team, a Pilot Movie starring Jesse Ventura & "Rowdy" Roddy Piper as two former wrestlers who become cops: During the target practice portion of the Police Academy Ventura's character displays remarkable marksmanship skills; he mentions that he was a SEAL (as he is in Real Life)
- The 2017 adaptation of Ghost in the Shell has Saito as an ex-Navy SEAL commando before he became a mercenary and later on, joined Section 9.
- In S.W.A.T., Officer Jim Street is a former Navy SEAL. He puts his demolition training to good use when the team is delayed by a locked gate.
- In the 87th Precinct novels, Cotton Hawes served in the navy during World War II. His experience allows him to identify a plane in a photograph as a Zero, as he had been on deck when his ship was strafed by one.
- Hawaii Five-0 (2010 remake) - Steve McGarrett (SEAL)
- Hawaii Five-O (the original) - Steve McGarrett, the head of the Five-O police unit, is a former U.S. Navy officer and a commander in the U.S. Naval Reserve. Several episodes had references to his past career.
- Magnum, P.I. - Magnum was in Vietnam as a SEAL. This pops up occasionally.
- Magnum, P.I. (2018) - Magnum in the remake is still a former SEAL, and served in Afghanistan, where he was a POW; he and several friends he met in captivity settled in Hawaii after leaving the service.
- NCIS: Los Angeles - Sam Hanna (SEAL)
- On Graceland, FBI Agent "Johnny" Tuttoro is ex-Navy, and he's a rare case of someone who wasn't a SEAL. During his time in the Navy Johnny did try out for the SEALs, but was injured during the infamous Hell Week and had to withdraw from training. He finished his time in the Navy and went pretty much straight into law enforcement afterward.
- President Theodore Roosevelt was essentially the Acting Secretary of the Navy when the Spanish American War broke out and he joined the Rough Riders in the Army's Cavalry. He was also the Police Commissioner of New York City.
- The Choirboys - Sergeant "Sperm-Whale" Whelan of the LAPD is also a USAF reservist. He therefore spends weekends and down-time from the police in flying transport and logistic missions from the USA to Vietnam and back ('The Choirboys'' is set in the early 1970's). This has humorous consequences. When on Monday morning the other cops are discussing where they went at the weekend and are coming out with things like "Took the kids to Venice Beach. Some rain." Whelan can laconically reply "nowhere much. Da Nang. Some flak. how about you?" When late getting back once, Whelan went straight to the station house in his USAF uniform.
- London's Burning - one of the firemen was also a reservist in the Royal Air Force and trained by the RAF to deal with aircraft fires or crash-landings. Which came in useful in the big series finale concerning a plane crash in London.
- Resident Evil - Chris Redfield is formerly from the U.S. Air Force and joined the Raccoon Police Department after being discharged.