A mistrial ends a trial without a valid final verdict, most commonly because of a hung jury, but also for reasons like serious juror or attorney misconduct, an evidentiary error too prejudicial to cure with an instruction, or an external event that undermines the fairness of continuing, such as improper contact with a juror. A mistrial is a significant, usually last-resort remedy, since it discards the time and resources already invested in the trial to that point.

After a mistrial, the case generally can be retried unless the mistrial resulted from prosecutorial or plaintiff misconduct intended to provoke it, or in some circumstances where double jeopardy or similar principles bar a retrial. Parties can also move for a mistrial themselves, arguing that a particular event — an improper remark by opposing counsel, an inadmissible statement blurted out by a witness — was so prejudicial that no curative instruction could fix it.

A simulated Juricratic matter's decision tree can model the risk of a mistrial as its own branch alongside win, loss, and settlement outcomes, since a mistrial resets the clock and cost structure of a case without resolving the underlying merits — a materially different consequence than an ordinary defense or plaintiff verdict that a single win-probability dial would obscure.

Trial counsel moves for a mistrial when an event at trial is so prejudicial that a limiting instruction cannot cure it, weighing the tactical cost of restarting the case against the risk of proceeding with a tainted trial. Because a mistrial often means retrying the case from the beginning, both sides typically treat the decision to seek one as a serious strategic calculation, not a routine objection.