What Is Double Jeopardy? Why You Cannot Be Tried Twice for the Same Crime

The principle appears in Athenian law, in the Roman maxim that no one should be troubled twice for the same cause, and in the Talmud. In English law it was argued over in the twelfth century between Henry II and Thomas Becket, who objected to clergy convicted in church courts being punished again by the king, and it settled into two pleas a defendant could make: autrefois acquit, that they had previously been acquitted of the charge, and autrefois convict, that they had previously been convicted of it. The Fifth Amendment to the American constitution put it in one clause in 1791: no person shall be subject for the same offence to be twice put in jeopardy of life or limb.

The reasons for the rule have been stated many times, most fully by the American Supreme Court in 1957. The state, with all its resources, should not be allowed to make repeated attempts to convict an individual, subjecting them to embarrassment, expense and ordeal and compelling them to live in continuing anxiety, and enhancing the possibility that even though innocent they may be found guilty. Behind that lie several separate concerns:

• •Finality: a verdict must at some point be the end of the matter, or no acquitted person is ever free
• •Equality of arms: a prosecutor who can retry until a jury convicts will eventually find one
• •The integrity of the jury: an acquittal that can be overturned by prosecuting again is not a verdict but an opinion
• •Restraint: the rule forces the state to prepare its case properly the first time

The rule has always had edges. A mistrial, where the jury cannot agree or the trial collapses, is not an acquittal, and the defendant can be tried again. A conviction overturned on appeal because of a legal error sends the case back for retrial, since the defendant asked for the verdict to be set aside. In federal systems the same act can be a crime under two sovereigns: in the United States a person acquitted in a state court can be tried in a federal court for the same conduct, which is how two of the police officers acquitted of beating Rodney King in 1992 were later convicted of violating his civil rights. And a civil claim is not a prosecution, so O. J. Simpson, acquitted of murder in 1995, was found liable for the same deaths by a civil jury in 1997 and ordered to pay damages.

In 1993 a black teenager, Stephen Lawrence, was murdered at a bus stop in south London, and the prosecution of the men suspected collapsed. A public inquiry into the police failures recommended in 1999 that the double jeopardy rule be reconsidered where compelling new evidence emerges, and the Criminal Justice Act 2003 did so for England and Wales: for about thirty of the most serious offences, the Court of Appeal can now quash an acquittal and order a retrial if there is new and compelling evidence that was not available at the first trial and a retrial is in the interests of justice. One of the men acquitted in 1996 was retried under the new law and convicted in 2012. Scotland, Australia and New Zealand have adopted similar rules, and the change is one of the largest to criminal procedure in the common-law world in a century.

The United States has not followed. The Fifth Amendment is read as absolute for the same sovereign, and no new evidence, however strong, allows a federal or state prosecutor to retry an acquittal. Most of continental Europe permits reopening a case in narrow circumstances, and the European Convention on Human Rights protects against double jeopardy while expressly allowing a retrial where new facts come to light or the first trial was fundamentally flawed.

The case for the reform is that a rule designed to stop oppressive prosecution should not shield a murderer from DNA evidence that did not exist when he was tried, and that an acquittal obtained by intimidating witnesses is not a verdict worth protecting. The case against is that every exception weakens the finality that gives an acquittal its meaning, that new evidence is easy to claim and hard to define, and that a defendant who knows the state may come back is never truly acquitted. Both sides agree on the underlying rule; the disagreement is about how absolute a protection has to be to work.

Much of the practical argument about double jeopardy turns on what counts as the same offence. A single act can break several laws, and prosecutors could in principle bring one charge, lose, and then try the defendant on another. American courts deal with this using a test from a 1932 Supreme Court case, Blockburger v United States: two offences are different if each requires proof of some fact that the other does not. Under this test, someone acquitted of robbery might still face a separate charge, such as a weapons offence, arising from the same events.

Lesser included offences work the other way. If a jury acquits someone of murder, they generally cannot then be charged with manslaughter for the same killing, because the elements of manslaughter were already contained in the murder charge that was tried. Legal systems also differ over appeals. In England and the United States the prosecution normally cannot appeal a jury's acquittal on the facts. In many civil law countries, such as Italy, the prosecution can appeal an acquittal to a higher court, and this is treated as part of one continuing trial rather than a second jeopardy.

The first person convicted after an acquittal was quashed under the 2003 law was William Dunlop. In 1989 Julie Hogg, a young mother, was murdered in Billingham in north-east England, and Dunlop was tried twice for the killing in 1991; both juries failed to agree, and he was formally acquitted. Years later, while in prison for another offence, he confessed to the murder, and he was then convicted of perjury for the evidence he had given at the trials. Under the old rule nothing more could be done about the murder itself, and Julie Hogg's mother campaigned for the law to change.

In 2006 the Court of Appeal quashed his acquittal, and he pleaded guilty to murder and was jailed for life. The case showed how tightly the new procedure is fenced in. Police cannot reopen an investigation into an acquitted person without the consent of the Director of Public Prosecutions, only one application to quash an acquittal can be made in each case, and the court can restrict reporting so that a retrial jury is not swayed by publicity. The law also applies to acquittals that took place before it came into force, which is why Dunlop's 1991 verdict could be revisited at all.

Systems differ sharply on whether a prosecutor may challenge an acquittal. In the United States, a jury's not guilty verdict in a criminal trial is generally final, and the prosecution cannot appeal it. Many continental European systems, including Germany's, allow the prosecution to appeal an acquittal to a higher court, which can hear the case again.

Those systems do not see this as breaking the rule against double jeopardy, because the appeal is treated as part of the same proceedings rather than a fresh prosecution, and the case is not finished until all appeals are exhausted. The difference reflects contrasting views of what a trial is: in one tradition, a single contest whose verdict should stand, and in the other, a process of getting to the right answer through review.

Double jeopardy is the rule that a person acquitted or convicted of an offence cannot be prosecuted for it again, rooted in Roman and English law and fixed in the American Fifth Amendment, and justified by finality, fairness and the integrity of the verdict. It does not cover mistrials, appeals, civil claims or a second sovereign, and since 2003 England, Scotland, Australia and New Zealand have allowed a retrial for the gravest offences where new and compelling evidence appears, while the United States has kept the rule absolute.