A mistrial may be declared sua sponte by the judge or upon motion by either party. Common grounds include juror misconduct, prejudicial statements by witnesses or counsel, improper evidence reaching the jury, or a deadlocked jury unable to reach a unanimous verdict. When a mistrial motion is made, the judge typically excuses the jury, hears arguments, and determines whether the error is so prejudicial that it cannot be cured by a limiting instruction. If a mistrial is declared over the defendant's objection in a criminal case, double jeopardy analysis applies to determine whether retrial is permitted under the "manifest necessity" standard.
Defense Counsel: "Your Honor, we move for a mistrial based on the prosecutor's reference to the defendant's prior convictions in violation of the court's in limine order."
Judge: "The jury having reported that they are hopelessly deadlocked after five days of deliberation, I am declaring a mistrial."
Judge: "The motion for mistrial is denied. I will issue a curative instruction to the jury."
Students frequently assume a mistrial means the defendant goes free. In most cases, the prosecution may retry the case. Only when a mistrial is caused by prosecutorial misconduct intended to provoke a mistrial motion does double jeopardy bar retrial.
Arizona v. Washington, 434 U.S. 497 (1978)
Held that a trial judge's finding of manifest necessity for a mistrial is entitled to great deference, and retrial is not barred by double jeopardy.
Oregon v. Kennedy, 456 U.S. 667 (1982)
Established that double jeopardy bars retrial after a defense-requested mistrial only when the prosecution's misconduct was intended to provoke the motion.
United States v. Perez, 22 U.S. (9 Wheat.) 579 (1824)
First articulated the manifest necessity doctrine, holding that a hung jury constitutes sufficient necessity to declare a mistrial.
| Mistrial | Dismissal |
|---|---|
| Trial is terminated before verdict | Case is terminated entirely |
| Case may be retried | With prejudice: case cannot be refiled |
| Declared by the judge sua sponte or on motion | May be voluntary (plaintiff) or involuntary (court) |
| Jury is discharged without reaching a verdict | No jury discharge issue (often pretrial) |
| Double jeopardy usually does not bar retrial | Dismissal with prejudice bars relitigation |
What is the difference between a mistrial and a dismissal?
A mistrial terminates the trial before a verdict due to a fundamental error; the case may be retried. A dismissal terminates the case itself; with prejudice it cannot be refiled.
Does a mistrial trigger double jeopardy protections?
Generally no. When declared due to manifest necessity (e.g., hung jury), retrial is allowed. But if the prosecution intentionally provoked a mistrial, retrial may be barred under Oregon v. Kennedy.
What are the most common grounds for declaring a mistrial?
Hung jury, juror misconduct or exposure to prejudicial information, prosecutorial misconduct, improper statements that cannot be cured by instruction, and sudden unavailability of a critical participant.
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