Double jeopardy is the constitutional rule that the government may not prosecute a person twice for the same offense after an acquittal or conviction. It comes straight from the Fifth Amendment's text: no person shall "be subject for the same offence to be twice put in jeopardy of life or limb." Once jeopardy attaches, the state gets one shot — with exceptions that matter as much as the rule itself.
This article explains when protection begins, what counts as the "same offense," why a federal prosecution can follow a state acquittal, and which outcomes leave the door open to a retrial. It publishes information, not legal advice; anyone with a real case needs counsel in the relevant jurisdiction.
The doctrine is one of the oldest in Anglo-American law, and its modern boundaries come mostly from Supreme Court cases rather than statutes. Those boundaries explain a recurring pattern in the news: a defendant acquitted in one courtroom is charged again in another, legally, without any violation of the rule.
When does double jeopardy protection begin?
Jeopardy "attaches" — meaning the protection starts — at a specific procedural moment, not at arrest or charging. In a jury trial, it attaches when the jury is sworn in. In a bench trial, when the first witness is sworn. In a guilty plea, at the court's acceptance of the plea. Before those moments, the prosecution can dismiss and refile charges freely.
Attachment matters because mistrials declared before jeopardy attaches carry almost no consequence. After attachment, the analysis gets harder: a retrial is generally barred if the defense requested the mistrial for prosecutorial overreach, but generally permitted if the defendant asked for the mistrial or if there was "manifest necessity" — a hung jury being the classic example.
Does an acquittal always end the case?
Yes, and this is the strongest form of the protection. When a jury acquits, the government cannot appeal the verdict, no matter how weak the evidence looked to observers or how badly the prosecution believes the trial went. Courts reason that an acquittal resolves the factual question in the defendant's favor, and reexamination is exactly what the clause forbids.
Convictions are treated differently in one respect: the government can appeal certain rulings made before the verdict, such as the suppression of evidence or the dismissal of some counts, as long as the appeal would not subject the defendant to a second trial on facts already resolved. A conviction can also be overturned on the defendant's appeal — and the government may then retry the person, because the reversal dissolves the first jeopardy. retrial after a successfully appealed conviction is routine, and it surprises many readers.
Related stories: What the exclusionary rule does, and when illegally obtained evidence still comes in · What a mistrial is, and what happens after one is declared.
Why can federal prosecutors charge after a state acquittal?
Because of the dual sovereignty doctrine, reaffirmed by the Supreme Court in Gamble v. United States (2019) by a 7-2 vote. The Court has long held that state and federal governments are separate sovereigns, and that successive prosecutions by different sovereigns are not prosecutions by "the same" sovereign for double jeopardy purposes. An acquittal in state court therefore does not bar a federal charge based on the same conduct, if federal law criminalizes it.
Gamble is the clearest recent statement. The defendant had pleaded guilty in Alabama state court to a gun possession offense and was then prosecuted federally for the same possession. The Supreme Court declined to overrule precedent dating to the nineteenth century, per the June 2019 opinion. Well-known examples where this rule shaped outcomes include the federal prosecution of the officers who beat Rodney King after their 1992 state acquittals, and the federal hate-crime case that followed Georgia's murder trial of the men who killed Ahmaud Arbery, which ended in convictions in February 2022. The doctrine remains one of the most criticized features of American criminal law among scholars, and several justices have questioned it in writing without mustering a majority.
What counts as the "same offense"?
Not every new charge counts as a new offense. The controlling federal test comes from Blockburger v. United States (1932): two statutes define the same offense if each requires proof of a fact the other does not. If one charge requires proof of an element the other lacks, they are different offenses and can both be charged — sometimes even in the same case, as multiple counts.
Greater-and-lesser offenses raise the sharpest questions. A homicide charge and a robbery charge arising from one incident are different under Blockburger. But if a defendant is acquitted of murder and convicted of the lesser included manslaughter on the same facts, no further murder prosecution is allowed. States apply variants: some have adopted the same-elements test, others broader protections against multiple punishments in a single prosecution.
What happens after a hung jury?
A hung jury is the classic "manifest necessity" justifying a mistrial, and the government may retry the case from scratch. This surprises readers who assume any trial ends the matter. The Supreme Court confirmed in Richardson v. United States (1984) that a retrial after a hung jury does not violate the clause, precisely because no verdict — acquittal or conviction — was reached.
The same logic applies when a defendant asks for the mistrial, which is treated as a strategic choice that waives the objection. The line courts police is prosecutorial conduct: if the prosecution intentionally goaded the defense into moving for a mistrial, retrial is barred, per Oregon v. Kennedy (1982). That standard is deliberately narrow and hard to satisfy.
Does double jeopardy apply to civil cases or juvenile proceedings?
Largely no, with one notable hybrid. The clause bars successive criminal prosecutions, not parallel civil litigation: a wrongful-death suit after an acquittal is constitutionally permissible, as the families of many homicide victims have done. Civil asset forfeiture was long treated as civil too, but the Supreme Court held in United States v. Ursery (1996) that civil forfeitures generally are not punishment for double jeopardy purposes.
Juvenile adjudications are the hybrid. In Breed v. Jones (1975), the Court held that a juvenile adjudication counts as jeopardy, so trying the juvenile again as an adult for the same conduct violates the clause. The protection is doctrinally consistent even if the forum changes — it protects against repeated exposure to criminal conviction, not against every state proceeding arising from the same events.
For more context, read What a grand jury does, and how it differs from a preliminary hearing.
For more context, read What an arraignment is, and what happens next.