In cop shows, when the good guys try to get information out of witnesses, the witnesses often don't want to tell the cops what they know, sometimes for real reasons, other times for no apparent reason. When this happens, the cop often threatens to charge the witness with obstruction for not coming forward with whatever information they want from them.
The witness is always shocked and scared by this because, in TV land, people on cop shows always believe that they can be arrested and thrown in jail for not telling the cop what they want to hear. (Though you can kinda forgive them for thinking that in a fictional universe where Stop, or I Will Shoot! is prevalent.)
In Real Life, obstruction of justice is only applied in the most blatant cases, when the witness is found later to actually have something to do with the crime (and has failed to take the Fifth Amendment or local equivalent), or when the prosecutor who gets the case is really, really frustrated. Charges may be laid when it is discovered that a person questioned in an investigation, who is not a suspect, has lied to the investigating officers. You can be called as a witness and be forced to testify or be held in contempt of court.
But only in major cases would the court bother and it would be up to the prosecuting attorney to decide this, not the police. No prosecutor is going to waste their time on someone solely because the cops complain they are uncooperative and might have witnessed something. Both the police and prosecutors know many witnesses will just lie and say they saw nothing unless the authorities have real evidence.
In most common law jurisdictions, most of the time, the right to remain silent allows any person who is questioned by police merely to refuse to answer questions posed by an investigator without giving any reason for doing so.
Note that there may be some Truth in Television in this. Just watch any police reality show. It's a matter of settled law in the United States that police are allowed to lie to those they question, including making empty threats. They're simply bluffing in the hopes that the witness actually is holding back evidence and that they're ignorant of the fact that the threat won't be followed through on.
Sometimes a prelude to the Jack Bauer Interrogation Technique. Automatically assumed in the event of a Dramatic Gun Cock or High-Altitude Interrogation. Also, a witness refusing to talk may be doing so because The Mob Boss Is Scarier. Compare Bavarian Fire Drill and Ineffectual Death Threats. Contrast the more effective Audit Threat.
- Subverted in the Ed Brubaker series Criminal, where an investigating officernote shows a photo of his target to the proprietor of the local Bad-Guy Bar and threatens "obstruction of justice" if he doesn't identify him. The bartender just smiles and tells him he's more than welcome to try and press charges on a 60 year old man for not recognising a particular face in a dark and crowded building.
- In the novel Black House, retired detective Jack Sawyer uses the Obstruction of Justice tactic on a group of boys being questioned on the whereabouts of their friend. It's made obvious to the reader that this is merely an attempt to impress the boys, as they are being silent about what they know because they're afraid they might be blamed for the friend's disappearance.
- In the Discworld City Watch novels, Vimes usually only charges people with obstruction as part of a raft of charges to make it clear that he's prepared to throw the entire book at them. There's an awesome moment in Night Watch where he threatens to charge one of the Cable Street Particulars with obstruction for refusing to sign and present identification when picking up prisoners.
Henry the Hamster: Arrest me? But I'm a copper, same as you!Vimes: Wrong again.
- Law & Order:
- This series is probably the worst offender. Any individual is threatened with Obstruction of Justice, and any business is threatened with a mob of NYPD officers searching everything and going through all their records (as if the NYPD has nothing better to do). People fold incredibly fast under these threats, because the show doesn't have the time to allow each witness to stonewall or play dumb. If one actually does hold out, it is the script equivalent of the Unmotivated Close Up: That specific witness has a critical piece of information. Its played with, however, in that its pretty clear that the cops involved know that there's no way they'd ever be able to carry out that threat and are only using it as an intimidation tactic, and sometimes the people they question also know it.
- A variation of the Empty Cop Threat comes from the prosecutors' frequent offers to "take the death penalty off the table" in exchange for information. New York State hasn't executed a prisoner since the 1960s, and the death penalty was declared unconstitutional by the state's highest court in 2004.
- A 2006 episode had McCoy attempting to appeal that ruling so he could get the death penalty for a man who had shot four grammar school students after killing a guard in his escape on the way to the courthouse for an appeal hearing of his earlier conviction for killing four people in a restaurant. The ruling is not overturned, but, in the end, the man is killed himself by a victim's father. McCoy thought he deserved it after nine (known) murders.
- Not every episode, but on occasion. In the episode "Toxic," a private security contractor was found going through the files of a journalist the FBI was visiting. After confirming his credentials, and after the journalist declined to press charges, Sinclair let the contractor off with a warning that if they ever caught him near their investigation again, he would charge him with obstruction of justice personally. When the contractor was caught there again, Sinclair didn't charge him - he did something more drastic.
- Another episode uses the trope: A man hires private security to find his stolen loot. The FBI is also on the case as people were kidnapped during the theft. The private security guys barge in as the FBI is about to arrest the kidnappers, which allows them to escape. Don immediately has both men arrested as accessory to the kidnappers, and warns their employer that if he sees any more of his employees following FBI agents around, he'll have him arrested under the same charges.
- Subverted on The Wire. Witnesses often flatly refuse to co-operate, because as the show frequently demonstrates, the threat of being killed by an angry drug dealer is much more credible. In one episode, the cops even acknowledge that the Obstruction of Justice charge is bogus, but if you lie under oath in a Grand Jury... It is done once to a perp's defence lawyer who knows where the suspect is hiding; McNulty threatens to send SWAT teams to his mother's house "until there isn't a house left to raid" and to do a tax audit of the lawyer's accounts. The latter threat hits home.
- Happens in practically every episode of Castle, which seems to contain a world full of suspects who will confess anything and everything to a firm but attractive female cop and a constantly-quipping civilian writer after enough pointed dialogue. Subverted when Beckett threatens a suspect after questioning him with "don't leave town" accompanied with a threat regarding what might happen if he did leave town. Castle inquires after the fact if she can even do that, to which she responds with something to the effect of "no, but he doesn't know that."
- The Star Trek: Enterprise episode "Judgment" could be described as what happens when the threat isn't so empty.
- A Touch of Frost. Jack Frost, a Detective Inspector in a provincial force, regularly threatens anyone who doesn't talk to him with visits from bodies varying in importance from the local Trading Standards Authority to Interpol. Particularly unconvincing as he treats everybody not on his team so badly that he's unlikely to get co-operation from the guy in the next office along let alone people in another country.
- Parodied in Supernatural:
Dean: Withholding information from the police is a capital offense.(The uncooperative witness doesn't really buy the threat. Sam clears his throat, with the meaning "Quit being an idiot, Dean.")Dean Uh, in some parts of the world, I'm sure.
- Subverted in Justified where the characters will call out US Marshal Raylan on his empty threats but ultimately give him the information he wants because they cannot be 100% sure that they are empty threats. After all, Raylan once told a gun thug to leave town in 24 hours and at the end of the deadline he actually gunned down the man in broad daylight. It also helps that most of the petty criminals he questions knows that he could bust them on some of the stuff they had done but since it is not really his jurisdiction he will let it slide if they cooperate.
- In NCIS, it's common for the team to threaten perps with being sent to Guantanamo Bay. In one case they get called on this, because the episode takes place during the Obama administration and sending new prisoners to Gitmo had been halted years ago. Gibbs responds by drugging the perp, putting him on a plane, and sending him some other random prison claiming it's Gitmo, as part of an elaborate hoax to make him think his terrorist employer was going to kill him.
- Double-subverted in an episode of NCIS: Los Angeles. Hetty threatens that she'll make sure a perp gets put in general population and make his very dangerous boss think he ratted him out. The perp objects that she's not allowed to do this, and Hetty agrees...and notes that it'll take about a week for the error to be sorted out, asking him if he thinks he can last that long. This intimidates the perp enough that he does rat out his boss.
- L.A. Noire: Cole Phelps and his partners make use of this trope quite some times. And it usually works out too, seeing how most people they encounter do have something to hide. Doesn't even have to be something concerning the particular investigation though; Hollywoodland was simply a Gangsterland back then.
- In the backstory of Ghost Trick, a suspect in an espionage case was put on the spot in this way by a rookie detective during interrogation. This pushed him to, in a fit of desperation, grab a gun, flee the premises and take a hostage. The outcome of the altercation and the suspect's hopeless mindset drives the game's plot and the many deaths that occur during it. And for the record, the suspect was innocent of the allegation and genuinely knew nothing about it.
- Played mostly straight in Whateley Universe story, Crime and Chaos. There's some evidence that the cop is purposely doing it just to get the person out of the way, and has no plans for it to actually stick. The person was, in fact, stonewalling, and the cop called a lawyer of dubious morality to handle it. This work was also an homage to Law and Order.