The Fifth Amendment to the U.S. Constitution provides that no person shall "be subject for the same offence to be twice put in jeopardy of life or limb." It's a relatively straightforward concept: The government can't prosecute someone more than once for the same crime. In practice, though, the double jeopardy prohibition can get complicated.
"Jeopardy" in the legal sense describes the risk brought by criminal prosecution. With notions of fairness and finality in mind, the Framers of the Constitution included the Double Jeopardy Clause to prevent the government from trying or punishing a defendant more than once.
Specifically, double jeopardy protects against:
A defendant facing any of these scenarios can hold up the Double Jeopardy Clause as a shield.
There are clear instances when this shield is available, such as when a jury has acquitted a defendant and the state brings the same charges a second time. (If the prosecution discovered new evidence of the defendant's guilt after the initial trial, too bad.) Double jeopardy also bars punishment in certain prototypical scenarios—for example, when a judge tries to resentence someone who has already served the punishment for the crime in question.
But there's often not an obvious answer as to whether the Double Jeopardy Clause applies. Certain principles guide courts in making the determination.
Double jeopardy applies to criminal cases only, not civil or administrative proceedings. That means, for example, that a defendant convicted of a crime isn't immune from a civil lawsuit for damages from the victim of the crime. It also means that the DMV can suspend and revoke drivers' licenses for the same actions that lead to criminal convictions. (An example is drunk driving, which a court and the DMV can punish separately.)
Double jeopardy prohibits different prosecutions for the same offense. This rule can come into play when the government brings a charge against someone for an incident, then prosecutes that person again for the same incident, only with a different charge. In that kind of situation, if each charge doesn't require that the prosecution prove at least one additional fact that the other doesn't, then the charges constitute the same offense under double jeopardy law. Here's an example showing how that rule works:
A man was convicted of joyriding, the elements of which were taking or operating a vehicle without the owner's consent. Later, the government charged him with auto theft, which consisted of joyriding while intending to permanently deprive the owner of the vehicle. To prove joyriding, a prosecutor wouldn't have had to prove anything more than what's required to prove auto theft. (Joyriding was a "lesser included" offense of auto theft.) Joyriding and auto theft therefore represented the same offense, and the auto theft prosecution violated the double jeopardy principle. (Brown v. Ohio, 432 U.S. 161 (1977).)
The government must place a defendant "in jeopardy" for the Fifth Amendment clause to apply. The simple filing of criminal charges doesn't cause jeopardy to "attach"—the proceedings must get to a further stage. Indeed, in many cases, the prosecution can drop charges through dismissal or nolle prosequi, then later refile them.
Generally, jeopardy attaches when the court swears in the jury. In a trial before a judge, jeopardy normally attaches after the first witness takes the oath and begins to testify.
But the empaneling of a jury—selecting jurors and swearing them in—doesn't actually mean that, whatever happens, the defendant can't be retried. Of course, if the jury acquits or convicts the defendant, the government normally can't re-prosecute. But if there was a conviction and an appellate court overturns the judgment, the prosecution might be able to retry the defendant. (Retrial sometimes isn't allowed, such as when an appeals court decides that the evidence was insufficient to convict the defendant.)
Criminal trials often end in something other than acquittal or conviction. There might be a mistrial because of jury misconduct, for example, or the jury might "hang," meaning that its members can't agree on a verdict. In these kinds of scenarios, even though a jury has already been sworn in and jeopardy has thereby attached, retrial is usually allowed. There are exceptions that can prevent retrial—for instance, severe misconduct by a prosecutor intended to create a mistrial. But, in lots of cases, the swearing in of the jury isn't the actual point of no return.
The attachment of jeopardy doesn't necessarily mean the government can't re-prosecute the defendant; jeopardy must also terminate. In other words, the case must in some sense conclude. The classic example is a jury reaching a verdict of either guilty or not guilty. Jeopardy also terminates when a judge finds the evidence insufficient to convict the defendant and enters a judgment of acquittal rather than letting the case go to the jury.
But just because a case ends doesn't mean that retrial is barred. Again, a hung jury often allows for a retrial. Similarly, if the defense consents to a mistrial, perhaps because of juror misconduct, the prosecution can usually re-prosecute the defendant. On the other hand, if a judge declares a mistrial over the defense's objection, the prosecution typically must show a critical need in order to retry the defendant. But that isn't as tough as it might seem. For example, retrial might well be allowed when, despite the defense's protest, a judge declares a mistrial because a juror stopped coming to court. (United States v. Wells, 790 F.2d 73 (10th Cir. 1986).)
The double jeopardy guarantee protects only against double prosecution or double punishment by the same "sovereign," or government. Even if the exact same conduct is at issue, a state prosecuting someone doesn't prevent the federal government from doing the same, and vice versa. (Learn more about state vs. federal prosecution.)
The federal prosecution of the officers who beat Rodney King illustrates the "separate sovereigns" principle. The State of California prosecuted the videotaped officers but failed to obtain any convictions. The 1992 Los Angeles Riots ensued. The federal government then prosecuted the officers for the same beating, alleging a violation of King's civil rights. The federal convictions were valid because separate sovereigns had tried the officers.
In the 2019 case Gamble v. United States, the U.S. Supreme Court reaffirmed the separate sovereigns doctrine. (139 S. Ct. 1960 (2019).) The defendant in that case had pleaded guilty in state court to the crime of possessing a firearm as a felon. The federal government also charged the man for the incident in question, but under an equivalent federal law. The Supreme Court noted that sovereigns have their own offenses, meaning that in this kind of case the defendant really isn't being prosecuted twice for the same crime. Accordingly, it decided that the second prosecution didn't violate the double jeopardy principle.
Prosecutors often file multiple charges against defendants for the same set of facts. For example, a prosecutor might charge someone with both assault and assault with a firearm for pointing a weapon at someone else. In that situation, if a jury were to convict the defendant of both offenses, double jeopardy might well block the judge from handing down a separate sentence for each crime.
Double jeopardy, like so many criminal law concepts, is intricate. And the legal rules throughout the country, while often similar, aren't always exactly the same. States, for instance, can have their own double jeopardy protections that supplement the Fifth Amendment. Also, some state legislatures and courts might take different approaches than others. If you want to know how or whether the double jeopardy principle applies to a situation you face, make sure to consult an experienced criminal defense attorney.