Jury nullification (US) or a perverse verdict (UK)[1][2] generally occurs when members of a criminal trial jury believe that a defendant is guilty, but choose to acquit him anyway because the jurors also believe that the law itself is unjust,[3][4] that the prosecutor has misapplied the law in the defendant's case,[5] or that the potential punishment for breaking the law is too harsh. Some juries have also refused to convict due to their own prejudices in favour of the defendant.[6]

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

Jurors cannot be punished for reaching a "wrong" decision (such as acquitting a defendant despite their guilt being proven beyond a reasonable doubt).[7]
A defendant who is acquitted cannot be tried again for the same alleged crime in front of another jury.[8]
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. Likewise, a jury can convict a defendant even if no law was actually broken, although such a conviction may be overturned on appeal. Nullification can also occur in civil trials.

Jury nullification?