Jury Nullification

Jury nullification occurs when jurors return a not guilty verdict even though the prosecution has proven the elements of the offense beyond a reasonable doubt, because they object to the law itself, its application in the case, or the potential punishment. It is a structural byproduct of two features common to common-law systems: the secrecy of jury deliberations and the double jeopardy rule, which bars retrial after acquittal. Because jurors cannot be punished for their verdict and an acquittal cannot be appealed, nullification is effectively unreviewable, even though it is not a formally recognized "right."

In the United States, courts distinguish between the power to nullify (which juries undeniably have) and any right to be told about it. Federal and most state courts forbid defense attorneys from urging nullification and decline to instruct juries on it; the leading modern statement is United States v. Dougherty, 473 F.2d 1113 (D.C. Cir. 1972), which acknowledged the power but rejected an instruction requirement. Earlier, Sparf v. United States, 156 U.S. 51 (1895), held that juries must take the law from the judge.

Historically prominent episodes include the 1670 trial of William Penn and William Mead in London, after which Bushel's Case established that jurors could not be punished for their verdicts; the 1735 acquittal of printer John Peter Zenger on seditious libel charges; and numerous Fugitive Slave Act acquittals in the 1850s North. In the 20th century, juries frequently refused to convict under Prohibition (1920–1933), contributing to political pressure for repeal.

Critics argue nullification can entrench injustice as well as resist it — Jim Crow-era Southern juries acquitted white defendants in racial violence cases. Comparable doctrines exist in the UK (the perverse verdict) and were curtailed in Canada by R v. Krieger, 2006 SCC 47. Advocacy groups such as the Fully Informed Jury Association campaign for explicit juror education on the practice.