A mistrial is a legal proceeding in which a trial is ended before a verdict can be reached because of a serious problem that prevents the court from conducting a fair trial. When a judge declares a mistrial, it generally means the existing trial cannot continue in its current form. Depending on the circumstances, the case may be tried again before a new jury.
The term often appears in news reports about high-profile criminal and civil cases, but what exactly does a mistrial mean, and why does a judge declare one?
What is a mistrial?
A mistrial occurs when something happens during a trial that seriously affects the fairness or integrity of the proceedings. The judge may determine that the problem cannot reasonably be corrected while allowing the trial to continue.
In a jury trial, for example, jurors may hear information that they were not supposed to hear. If that information could unfairly influence their decision, simply instructing the jury to ignore it may not be enough. In such circumstances, the judge may conclude that the trial cannot proceed fairly and declare a mistrial.
A mistrial does not mean that the defendant has been found guilty or innocent. Instead, it means the trial ended without a valid final verdict.
Why do judges declare a mistrial?
There are several circumstances that can lead to a mistrial. The exact rules differ depending on the jurisdiction and the type of case, but common reasons include:
1. Serious jury misconduct
A mistrial may be considered if jurors engage in serious misconduct, such as discussing the case improperly, conducting independent research or violating important court instructions.
Minor violations do not necessarily result in a mistrial. The judge typically considers whether the misconduct has created significant prejudice.
2. Improper evidence
Evidence that was not legally admissible may sometimes be presented to the jury. If the information is particularly damaging and cannot realistically be disregarded, the judge may determine that a fair trial is no longer possible.
3. Prejudicial publicity
In some cases, extensive publicity surrounding a trial can create concerns about whether jurors can remain impartial. If circumstances make a fair proceeding impossible, a mistrial can become an issue.
4. Serious procedural errors
Major mistakes involving the presentation of evidence, jury instructions or other trial procedures can potentially lead to a mistrial when the error substantially affects the fairness of the proceeding.
5. Hung jury
One of the best-known situations is a hung jury. This occurs when jurors cannot reach the required agreement on a verdict after reasonable efforts and deliberation.
For example, in a criminal case requiring a unanimous verdict, a jury might remain divided despite extended deliberations. The judge may then declare a mistrial because the jury is unable to reach a verdict.
Who can request a mistrial?
A mistrial can sometimes be requested by either side in a case. For example, the defense or prosecution may ask the judge to declare one after a serious incident occurs.
However, requesting a mistrial does not automatically mean the judge will grant it. The judge considers the circumstances, applicable law and whether the problem can be remedied without ending the trial. In some situations, a judge may declare a mistrial without either party requesting it.
What happens after a mistrial?
The consequences depend heavily on why the mistrial occurred.
If a mistrial results from a hung jury, the prosecution may generally have the option of bringing the case to trial again in jurisdictions where applicable law permits it. The next trial may involve a new jury.
If the mistrial was caused by a serious legal error, the court may consider whether the problem can be corrected through another proceeding.
A mistrial therefore does not necessarily end the underlying case. It usually ends that particular trial.
Does a mistrial mean the defendant is innocent?
No. A mistrial is not the same as an acquittal.
An acquittal means the defendant has been found not guilty, while a mistrial means the trial ended without a final verdict on the relevant charges.
This distinction is important because a mistrial can sometimes be followed by another trial, subject to constitutional protections and other applicable laws.
Can someone be retried after a mistrial?
In many legal systems, a retrial after a mistrial may be possible, but it is not automatically permitted in every situation.
In the United States, for example, the constitutional protection against double jeopardy can become important. Whether prosecutors can retry a defendant after a mistrial can depend on why the mistrial occurred and whether the defendant agreed to or requested it.
When a mistrial results from a hung jury, retrial is generally permitted under U.S. law. Other situations can be more complicated, particularly when the mistrial was caused by prosecutorial or judicial misconduct. The specific law of the jurisdiction therefore matters greatly.
Mistrial vs. dismissal
A mistrial should also be distinguished from a dismissal.
A mistrial concerns the trial itself and means the proceeding ended without a valid verdict. A dismissal, by contrast, involves ending the case or particular charges through a court order. A case can sometimes continue after a mistrial, whereas a dismissal may have different legal consequences depending on whether it is with or without prejudice.
Why does a mistrial matter?
The purpose of a mistrial is not simply to give one side another opportunity. Its central purpose is to protect the fairness and integrity of the judicial process.
Courts must ensure that jurors base their decisions on properly admitted evidence and applicable legal instructions. When a serious problem makes that impossible, ending the trial may be considered preferable to allowing an unreliable verdict.
The bottom line
A mistrial means that a trial has ended before a valid verdict because a serious problem prevented—or was considered likely to prevent—a fair proceeding.
It does not automatically mean that the defendant is guilty or innocent, and it does not necessarily mean the case is over. Depending on the circumstances and the law governing the case, another trial may be possible.
Because the legal consequences of a mistrial vary from one jurisdiction to another, the reason for the mistrial and the applicable law are critical to understanding what happens next.
