When Is It Illegal to Lie?

Obviously, when you like big butts, you cannot lie, but how dishonest can you be in other situations? Pretty dishonest, it turns out. In most day-to-day circumstances, you can be as duplicitous as you like and no one can throw you in jail for it—you can tell people your uncle works at Nintendo, or your arm is made of chocolate, and it’s not a crime (usually). The first amendment gives us wide latitude for saying whatever we want, even if it’s bullshit, but there are exceptions—and lying when you’re not legally allowed to can have dire consequences. Here’s a guide to when lying could lead to prison, fines, and general disgrace.

It’s not a good idea to lie in these circumstances

Laws vary from jurisdiction to jurisdiction, and there’s always the possibility of an exception to any of these situations, but in general, here are the main situations where it is illegal to tell a lie.

When involved in a federal investigation

According to 18 U.S. Code § 1001, you can be fined or imprisoned for making “any materially false, fictitious, or fraudulent statement or representation” about “any matter within the jurisdiction of the executive, legislative, or judicial branch of the Government of the United States.” Pretty broad, right? You don’t have to be under oath, and you don’t have to know the person you’re lying to is a federal agent—it could be a casual conversation in McDonald’s. People have been convicted under this statute for lying to people who weren’t even part of the government. You don’t have to be guilty of the underlying crime the feds are looking into either. Martha Stewart, Scooter Libby, and George Papadopoulos all went down due to this law.

When under oath

You can’t lie in court. Perjury is a serious crime. The finer details vary from state to state and situation to situation, but knowingly making false statements while under oath is almost always a felony. And it’s not just lying in criminal court—perjury charges could be filed against you for lying under oath in a civil deposition or a written affidavit or declaration, too. Oh, and lying to congress.

When you are under arrest

The fine details vary from jurisdiction to jurisdiction, but in the United States, you can be prosecuted for lying to the police if you’ve been arrested, even if you’re lying about your own involvement in a crime. This is why you shouldn’t say anything to cops except “I’m remaining silent” and “I’d like a lawyer.”

When you are being “lawfully detained” by the police

Generally, you can exercise your right to remain silent in an interaction with the police, but there are exceptions. You may be required to provide police with your name, or your driver’s license and registration if you’re in a car, sometimes upon request, and sometimes if you’re being “lawfully detained,” depending on the state. If you lie in this situation, it may well be a crime. If you are talking to a cop who isn’t investigating a crime, and you’re not under arrest or being detained, it’s no more illegal to lie to them than anyone else. So feel free to give fake digits to an off-duty cop who wants to date you.

If you are being asked about a crime you witnessed

Do not lie to the police to protect your friend who committed a crime, or really any time the police are investigating a crime. Depending on your state, you could be charged with obstruction of justice, accessory after the fact, making false statements, and more. Luckily, you are generally not under any obligation to help police with their investigations. Other than providing your name or driver’s license and registration (if you’re driving), you usually don’t have to talk to police at all. So don’t offer any information. Instead of saying, “He was with me when the liquor store was robbed,” say, “I want to remain silent.”

When filing a police report

Filing a false police report is crime.

On many kinds of financial disclosure documents, including your taxes

The specifics of the kinds of financial documents upon which you can’t lie is too vast to get into here, (and if you’re a corporate officer tasked with this, you shouldn’t be getting information about it from this website), but we all file tax returns. Knowingly and willingly lying on them could be a crime.

When you’re advertising something

Various state and federal laws make it a crime to provide inaccurate or misleading information (or omit some kinds of information) in advertisements. Advertisers have serious leeway in making statements that are almost lies, or statements that are “puffery,” though, so don’t expect them to arrest Guiseppe because he didn’t actually serve you the world’s best pizza.

If you’re committing fraud

This is a bit of a fine distinction, but if you lie to commit fraud or some other crime, the lie itself isn’t the illegal part. It’s the crime you’re lying in order to commit that’s illegal. So you won’t be charged with anything for telling people you’re a doctor, but if they pay you, and you perform a nose job on ‘em, you’ve probably committed two crimes (at least).

Going to jail isn’t the only possible consequence of lying

The first amendment prevents the government from charging you with a crime for lying in most situations, but civil consequences are something else. There are way too many ways dishonesty can get you sued, and way too many details to get into here, but super-simplified: If your lie results in damages of some kind to others, they can sue you, whether it’s a deliberate lie or a lie of omission, so be aware of the consequences of your actions, watch your tongue, and try to only deceive people who don’t have the means to seek legal redress. Or just don’t lie to anyone.