What is double jeopardy?

Where the rule comes from

The Fifth Amendment says no person shall “be subject for the same offence to be twice put in jeopardy of life or limb.” Through the Fourteenth Amendment it binds the states as well as the federal government, and most state constitutions contain their own version. The idea is old: the government, with all its resources, should not be able to keep prosecuting someone until it gets the verdict it wants.

What it actually bars

• A second prosecution for the same offense after an acquittal.
• A second prosecution for the same offense after a conviction.
• Multiple punishments for the same offense in the same proceeding.

An acquittal cannot be appealed by the prosecution, even if the judge made an error of law in the defendant's favor or new evidence surfaces later. That is the hardest edge of the rule and the one most often misunderstood.

When jeopardy attaches

Protection begins at a specific moment: when the jury is sworn in a jury trial, or when the first witness is sworn in a bench trial. Charges dismissed before that point — at a preliminary hearing, for example — can usually be refiled. A guilty plea also attaches jeopardy once the court accepts it.

The exceptions people are surprised by

• Separate sovereigns. A state and the federal government are different sovereigns, so both may prosecute the same conduct — the rule reaffirmed in Gamble v. United States (2019). Two states may each prosecute where the conduct crossed state lines, and tribal and federal prosecutions can coexist. Some states limit this by their own statutes.
• Mistrials. If a trial ends in a hung jury, or a mistrial is declared out of “manifest necessity,” retrial is allowed. A mistrial the defendant requested also usually allows retrial, unless the prosecutor deliberately provoked it.
• Appeals by the defendant. Win an appeal and the conviction is usually vacated, not converted into an acquittal, so the state can retry. The exception is a reversal because the evidence was legally insufficient — that counts as an acquittal.
• Different offenses. Under the Blockburger test, two charges are different offenses if each requires proof of a fact the other does not. A single incident can therefore support convictions for, say, burglary and theft.
• Civil cases are not jeopardy. Being sued for the same conduct is not a second prosecution, which is why an acquitted defendant can still face a wrongful-death claim.

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Lesser included offenses

A conviction or acquittal on a greater offense bars a later prosecution for a lesser offense contained within it, and vice versa. Someone acquitted of murder cannot later be tried for manslaughter on the same killing if manslaughter was necessarily included in the first case.

Collateral estoppel

Even when two charges are technically different offenses, a jury's decision on a factual question can bind the government. If an acquittal necessarily found that the defendant was not present at a robbery, the state cannot prosecute a second robbery count from the same event that depends on his presence (Ashe v. Swenson, 1970).

Where it does not reach

Retrial after a conviction is overturned for a defect in the process; prosecution for a related offense that was not yet complete at the first trial, such as a homicide charge after the victim of an earlier assault dies; civil forfeiture, license suspensions and professional disciplinary proceedings, which are treated as civil. Probation-revocation hearings are also not a second prosecution.

Practical takeaway

Double jeopardy is a strong protection, but it turns on technical questions: which sovereign, which offense, and when jeopardy attached. If you face charges in more than one court, or a new charge after an earlier case over the same events, a criminal defense lawyer should review whether a double jeopardy motion is available — it must normally be raised before the second trial.

The rule also protects people only against criminal punishment, so administrative sanctions and fines imposed alongside a conviction are usually allowed.