thumb|right|upright=1.0|The Trial of the [[Seven Bishops by John Rogers Herbert]]

Jury nullification, also known as jury equity or as a perverse verdict, is a decision by the jury in a criminal trial resulting in a verdict of not guilty even though they believe a defendant has broken the law. The jury's reasons may include the belief that the law itself is unjust, Some juries have also refused to convict due to their own prejudices in favor of the defendant.

Nullification is not an official part of criminal procedure, but is the logical consequence of two rules governing the systems in which it exists:

  1. Jurors cannot be punished for the verdict they make.
  2. In many jurisdictions, a defendant who is acquitted cannot be tried a second time for the same offense.<!--double jeopardy is no longer banned in England-->

A jury verdict that is contrary to the letter of the law pertains only to the particular case before it; however, if a pattern of acquittals develops in response to repeated attempts to prosecute a particular offence, this can have the de facto effect of invalidating the law. Such a pattern may indicate public opposition to an unwanted legislative enactment. It may also happen that a jury convicts a defendant even if no law was broken, although such a conviction may be overturned on appeal. Nullification can also occur in civil trials; unlike in criminal trials, if the jury renders a not liable verdict that is clearly at odds with the evidence, the judge can issue a judgment notwithstanding the verdict or order a new trial.

Background

thumb|upright=1.6|right|A 19th-century jury

In the past, it was feared that a single judge or panel of government officials might be unduly influenced to follow established legal practice, even when that practice had drifted from its origins. In most modern Western legal systems, judges often instruct juries to act only as "finders of fact", whose role it is to determine the veracity of the evidence presented, the weight accorded to the evidence, The argument has been raised that prosecutors are not allowed to seek jury nullification, and therefore defendants should not be allowed to seek it either; however, for a prosecutor to nullify a law in this context would require negating the presumption of innocence. For this reason, prosecutorial nullification is typically defined as declining to prosecute. Nevertheless, there is little doubt as to the ability of a jury to nullify the law. Today, there are several issues raised by jury nullification, such as:

  1. Whether juries can or should be instructed or informed of their power to nullify.
  2. Whether a judge may remove jurors "for cause" when they refuse to apply the law as instructed.
  3. Whether a judge may punish a juror for practicing jury nullification.
  4. Whether all legal arguments, except perhaps on motions to exclude evidence, should be made in the presence of the jury.

In some cases in the United States, a stealth juror will attempt to get on a jury in order to nullify the law. Some lawyers use a shadow defense to expose the jury to information that would otherwise be inadmissible, hoping that evidence will trigger a nullification.

Common law precedent

thumb|Even prior to [[Bushel's Case, Sir Nicholas Throckmorton, a non-Episcopalian English Dissenter, or Nonconformist, outside the established Church of England, was acquitted by a jury despite hostility of the judges.]]

The early history of juries supports the recognition of the de facto power of nullification. By the 12th century, common law courts in England began using juries for more than administrative duties. Juries were composed primarily of "laymen" from the local community and provided a somewhat efficient means of dispute resolution with the benefit of supplying legitimacy. The general power of juries to decide on verdicts was recognised in the English Magna Carta of 1215, which put into words existing practices:

Largely, the earliest juries returned verdicts in accordance with the wishes of the judge or the Crown. This was achieved either by "packing the jury" or by "writs of attaint". Juries were packed by hand-selecting or by bribing the jury so as to return the desired verdict. That was a common tactic in cases involving treason or sedition. In addition, the writ of attaint allowed a judge to retry the case in front of a second jury when the judge believed the first jury returned a "false verdict". If the second jury returned a different verdict, that verdict was imposed, and the first jury was imprisoned or fined.

That history is marked by a number of notable exceptions, several of which claim rights commonly recognized as fundamental in modern democratic societies, such as freedom of speech and of the press, and freedom of religious practice. In 1554, a jury acquitted Sir Nicholas Throckmorton but was severely punished by the court. Almost a century later, in 1649, in the first known attempt to argue for jury nullification, a jury likewise acquitted John Lilburne for his part in inciting a rebellion against Oliver Cromwell's regime. Lilburne had been charged with seditious libel for the publication of articles critical of the government; the jury were instructed to give a verdict only on whether the text was published, and to leave the issue of libel to the judge, while Lilburne argued the jury should give a general verdict and should judge whether the law's restraint on speech against the government was just. The theoretician and politician Eduard Bernstein wrote of Lilburne's trial: