In common law jurisdictions, an acquittal means that the criminal prosecution has failed to prove that the accused is guilty beyond a reasonable doubt of the charge presented. It certifies that the accused is free from the charge of an offense, as far as criminal law is concerned. The finality of an acquittal is dependent on the jurisdiction. In some countries, such as the United States, an acquittal prohibits the retrial of the accused for the same offense, even if new evidence surfaces that further implicates the accused. The effect of an acquittal on criminal proceedings is the same whether it results from a jury verdict or results from the operation of some other rule that discharges the accused. In other countries, like Australia, Canada and the UK, the prosecuting authority may appeal an acquittal similar to how a defendant may appeal a conviction — but usually only if new and compelling evidence comes to light or the accused has interfered with or intimidated a juror or witness.
In Canada, the prosecution may appeal different types of decisions, judgments, or orders in criminal cases.
Under Section 676(1) of the Criminal Code of Canada, the Crown may appeal against:
A judgment or verdict of acquittal or a verdict of not criminally responsible on account of mental disorder of a trial court in proceedings by indictment on any ground of appeal that involves a question of law alone. [s. 676(1)(a)]
An order of a superior court of criminal jurisdiction that quashes an indictment or in any manner refuses or fails to exercise jurisdiction on an indictment. [s. 676(1)(b)]
An order of a trial court that stays proceedings on an indictment or quashes an indictment. [s. 676(1)(c)]
The sentence passed by a trial court in proceedings by indictment, unless that sentence is one fixed by law, if leave of the court of appeal or a judge thereof is given. [s. 676(1)(d)]
Under section 676(1.1), the prosecution may, with leave of the court of appeal or a judge thereof, appeal against an acquittal in a summary offence proceeding or a sentence passed with respect to a summary conviction as if the summary offence proceeding was a proceeding by indictment if there was no appeal with respect to the summary conviction, the summary conviction offence was tried with an indictable offence, and there was an appeal in respect of the indictable offence.
Section 676(2) defines an acquittal as "an acquittal in respect of an offence specifically charged where the accused has, on the trial thereof, been convicted or discharged under section 730 of any other offence."
The prosecution may also appeal a decision where the judge imposes a sentence which is less than that required by law, where the judge does not impose a sentencing order, or where the judge does not impose a sentence of life imprisonment without parole for murder (the last provision being unconstitutional as concerning R. v. Bissonnette)
Scots law previously had two acquittal verdicts: not guilty and not proven. Secondary legislation laid before the Scottish Parliament in December 2025 provided for the abolition of the not proven verdict on 1 January 2026.
In England and Wales, which share a common legal system, the Criminal Justice Act 2003 creates an exception to the double jeopardy rule, by providing that retrials may be ordered if "new and compelling evidence" comes to light after an acquittal for a serious crime. Also, the Criminal Procedure and Investigations Act 1996 permits a "tainted acquittal" to be set aside in circumstances where it is proved beyond reasonable doubt that an acquittal has been obtained by violence or threats of violence to a witness or juror/s.
In modern England and Wales, and in all countries that substantially follow English criminal procedure, an acquittal normally results in the immediate liberation of the defendant from custody, assuming no other charges against the defendant remain to be tried. However, until 1774, a defendant acquitted by an English or Welsh court would be remanded to jail until he had paid the jailer for the costs of his confinement. It was known for acquitted persons to die in jail for lack of jailer's fees.
With one exception, the prosecution in the United States cannot appeal an acquittal because of constitutional prohibitions against double jeopardy. The U.S. Supreme Court has ruled:
If the judgment is upon an acquittal, the defendant, indeed, will not seek to have it reversed, and the government cannot. U.S. v. Sanges, 144 U.S. 310 (1892). Ball v. U.S., 163 U.S. 662, 671 (1896)
A verdict of acquittal, although not followed by any judgment, is a bar to a subsequent prosecution for the same offense. Ball, supra, at 672.
Society's awareness of the heavy personal strain which a criminal trial represents for the individual defendant is manifested in the willingness to limit the Government to a single criminal proceeding to vindicate its very vital interest in enforcement of criminal laws. United States v. Jorn, 400 U.S. 470, 479 (1971)
Whether the trial is to a jury or, as here, to the bench, subjecting the defendant to postacquittal factfinding proceedings going to guilt or innocence violates the Double Jeopardy Clause. Smalis v. Pennsylvania, 476 U.S. 140 (1986)