West's Encyclopedia of American Law | Mistrial

A courtroom trial that has been terminated prior to its normal conclusion. A mistrial has no legal effect and is considered an invalid or nugatory trial. It differs from a "new trial," which recognizes that a trial was completed but was set aside so that the issues could be tried again.

A judge may declare a mistrial for several reasons, including lack of jurisdiction, incorrect jury selection, or a deadlocked, or hung, jury. A deadlocked jury—where the jurors cannot agree over the defendant's guilt or innocence—is a common reason for declaring a mistrial. Extraordinary circumstances, such as death or illness of a necessary juror or an attorney, may also result in a mistrial. A mistrial may also result from a fundamental error so prejudicial to the defendant that it cannot be cured by appropriate instructions to the jury, such as improper remarks made during the prosecution's summation.

In determining whether to declare...