A mistrial occurs when a jury is unable to reach a verdict and there must be a new trial with a new jury; or there is a serious procedural error or misconduct that would result in an unfair trial, and the judge adjourns the case without a decision on the merits and awards a new trial.
With regards to procedural errors or misconduct, grounds for a judge to order a mistrial include improper admission of prejudicial evidence; misconduct by the court, counsel, parties, or witnesses; and jury errors, among other grounds.
Mistrials can occur in both civil and criminal cases. Federal Rules of Criminal Procedure Rule 26.3 states that “Before ordering a mistrial, the court must give each defendant and the government an opportunity to comment on the propriety of the order, to state whether that party consents or objects, and to suggest alternatives.”
There is no set time requirement for when to make a mistrial motion, but the movant should generally request the mistrial immediately after the grounds for doing so appear, to avoid waiving the issue and to allow the court the opportunity to correct the error before it can have prejudicial effect if possible.
[Last updated in July of 2023 by the Wex Definitions Team]