What does double jeopardy mean?

Double jeopardy means being tried twice for the same crime, and the Fifth Amendment forbids it. The exact text, ratified on December 15, 1791, declares that no person shall be subject for the same offence to be twice put in jeopardy of life or limb. The protection prevents the government from retrying a defendant after a verdict of acquittal, retrying a defendant after a conviction without successful appeal of that conviction, or imposing multiple punishments for the same offense in a single proceeding.

The Supreme Court applied the protection to state prosecutions in Benton v. Maryland (1969) through the Fourteenth Amendment Due Process Clause, overturning the contrary rule from Palko v. Connecticut (1937). Three core protections flow from the clause. First, after a jury or judge acquits a defendant, the government has no right to appeal or retry, even if new evidence emerges, even if the prosecutor mishandled the case, and even if jurors made factual errors. Second, after a final conviction, the prosecution cannot retry the defendant on the same charge to seek a harsher sentence or different result. Third, courts cannot stack multiple convictions or punishments for what counts as a single offense, applying the same elements test from Blockburger v. United States (1932), which asks whether each charged statute requires proof of a fact the other does not.

Several exceptions and limits apply. The dual sovereignty doctrine, recognized in Heath v. Alabama (1985) and reaffirmed in Gamble v. United States (2019), allows separate state and federal prosecutions for the same conduct because each sovereign vindicates its own interests. A mistrial declared without manifest necessity, such as a hung jury or a defense motion for mistrial, generally permits retrial under United States v. Perez (1824) and United States v. Dinitz (1976). A successful defense appeal allows retrial because the original conviction has been wiped away, although Burks v. United States (1978) bars retrial after a court finds insufficient evidence to convict.

Civil and criminal proceedings are not the same offense, so a defendant acquitted of murder may still face a wrongful death suit, as O.J. Simpson did after his 1995 acquittal and 1997 civil verdict. Jeopardy attaches at specific moments: when the jury is sworn in jury trials, when the first witness is sworn in bench trials, and when a guilty plea is accepted. Naturalization candidates should know that this safeguard means government does not get unlimited chances to convict.