What Is a Mistrial? A Plain Guide to When a Trial Ends Without a Verdict

Most trials end with a verdict. The jury or judge decides the case, and the parties move on to sentencing, appeals or simply going home. Occasionally, though, a trial ends without any valid result at all. When that happens, the judge declares a mistrial.

The word sounds dramatic, but a mistrial is not a ruling on who was right. It means the trial cannot continue fairly or cannot reach a lawful decision, so it is stopped. This guide explains why mistrials happen and what they mean for the people involved.

What a Mistrial Means

A mistrial is a trial that ends early, or ends without a verdict, because of a serious problem. The judge declares it on the record, and the proceedings stop. Any evidence presented and any progress made toward a decision are set aside.

Importantly, a mistrial is not an acquittal and not a conviction. In a criminal case, the defendant is neither found guilty nor cleared. In a civil case, neither side wins. The case returns to roughly where it stood before trial, and the parties decide what to do next.

Common Reasons for a Mistrial

Judges do not declare mistrials lightly, because trials take a great deal of time and money. They usually do so only when continuing would be unfair or impossible. Several situations come up again and again.

A Hung Jury

The most familiar cause is a jury that cannot agree. Criminal trials in the United States generally require a unanimous verdict for serious charges, and the Supreme Court confirmed in Ramos v. Louisiana in 2020 that this applies in state courts as well as federal ones. If jurors remain deadlocked after genuine effort, the judge may declare a mistrial. Before doing so, many judges give the jury further instructions encouraging them to keep deliberating, sometimes known as an Allen charge after an 1896 Supreme Court case.

Misconduct or Prejudicial Errors

A mistrial can also follow serious misconduct. Examples include a juror researching the case online, a juror discussing the case with outsiders, or a lawyer making improper remarks that the jury cannot be expected to ignore. If inadmissible and highly damaging evidence reaches the jury, a judge may decide that no instruction to disregard it would be enough.

Practical Problems

Sometimes the cause is simply practical. A judge, lawyer or juror may become seriously ill, too many jurors may drop out to continue, or the court may discover it lacks authority to hear the case. In these situations, the trial cannot carry on properly.

How a Mistrial Is Requested

Either side can ask for a mistrial by making a motion, usually right after the problem appears. The judge can also declare one without a request. The judge weighs whether the problem can be fixed, for example by replacing a juror with an alternate or by giving the jury a clear instruction, before taking the more drastic step of ending the trial.

Can the Case Be Tried Again?

In many cases, yes. The Fifth Amendment protects people from being tried twice for the same offense, but courts have long held that this does not always bar a new trial after a mistrial. In United States v. Perez in 1824, the Supreme Court said a retrial is allowed when there was a manifest necessity for ending the first trial, and a genuinely deadlocked jury is the classic example.

When the defendant asks for the mistrial, a retrial is generally permitted as well. A narrow exception, recognized in Oregon v. Kennedy in 1982, applies when the prosecution deliberately provoked the defendant into requesting one. In rare circumstances, a judge may instead dismiss the case with prejudice, which means it cannot be brought again.

What Happens in Practice

After a mistrial, prosecutors or plaintiffs decide whether to retry the case, negotiate a plea or settlement, or drop it. A hung jury can reveal how jurors viewed the evidence, which often shapes those choices. For a defendant, the period after a mistrial can bring both relief and uncertainty while that decision is made.

The Bottom Line

A mistrial is a safety valve. It stops a trial that cannot produce a fair or lawful result, without deciding the case either way. Most of the time the dispute continues in another form, through a new trial, a negotiated outcome or a dismissal.

If you are a party, witness or juror in a case where a mistrial is declared, ask the lawyer involved or the court clerk what comes next, since procedures and timelines vary by court and jurisdiction. This guide is general information, not legal advice.