A criminal trial that ends before it concludes results in a mistrial. Considered to be a drastic remedy, a judge must only grant a mistrial when no other adequate solution exists. The reasons for a mistrial will often decide whether the prosecution gets another case to present its case to a jury without violating double jeopardy principles.
What Is a Mistrial?
A mistrial means a judge has permanently halted a criminal trial before it concludes. The most common source of a mistrial is the jury’s failure to return a unanimous verdict (a situation known as a hung jury). Another example is when an attorney or a witness makes prejudicial statements that can't be corrected even by telling the jurors to disregard the statements. Serious misconduct by a party will also warrant a mistrial. Judges may also declare a mistrial upon learning that jurors have researched the case on their own on the internet.
When Can a Judge Declare a Mistrial?
Either side in a criminal case may move for a mistrial, and the court itself may declare one on its own. The process varies, depending on the reason for the mistrial.
Hung (Deadlocked) Jury
If the court is convinced that the jury cannot come to a unanimous decision, even with gentle urging from the judge and the assurance that they are doing as good a job as any jury would, the judge will declare a mistrial. The defense and prosecution will generally have to live with the judge’s decision.
Prosecutorial Misconduct
Now and then, prosecutors will cross the line with respect to proper trial tactics, by deliberately introducing inadmissible evidence or purposefully asking improper questions that are designed to put information before the jury that the jury should not hear. When this happens, defendants often ask for a mistrial due to fear that the jury has been permanently tainted. If the judge feels that the behavior was extreme and the jury cannot be successfully admonished (strongly directed) to disregard the incident, the judge will declare a mistrial.
Manifest Necessity
Sometimes, circumstances beyond the control of the court must result in a mistrial. For example, the death of the presiding judge will result in a mistrial. Or if several jurors become ill and the number of jurors falls below what's required under the law, the judge will declare a mistrial.
What Happens After a Judge Declares a Mistrial?
A mistrial doesn't necessarily mean the end of the case. In fact, in most cases, the prosecutor will be allowed to retry the case. Retrying a case, however, involves significant resources and may result in the parties negotiating a plea deal to avoid another trial. If a defendant objects to the mistrial or a prosecutor instigated the mistrial, double jeopardy principles may prohibit a second trial.
Does Double Jeopardy Prohibit Retrying a Case That Ended in a Mistrial?
Any attempted retrial in a criminal case must pass muster with none other than the U.S. Constitution’s provision that no person may “be subject for the same offence to be twice put in jeopardy of life or limb” (the Double Jeopardy Clause). Allowing the prosecutor to retry a case (a “second” time) following a mistrial might seem like a clear violation of double jeopardy, but the law isn’t that simple.
A mistrial results in no decision or verdict coming down from the jury. Because there’s been no resolution (such as there would be with an acquittal), double jeopardy doesn’t always prohibit a retrial. It comes down to unfairness and the competing interests at play—the defendant’s interest in reaching a verdict with one trial and the government’s interest in seeking justice through one full and fair trial. The interest that wins out depends on why and how the mistrial came about. If the defendant opposes a mistrial, the prosecutor must show that a “manifest necessity” exists for a retrial. (Arizona v. Washington, 434 U.S. 497 (1978).)
When Can a Defendant Be Retried After a Mistrial?
As noted above, mistrials happen for a variety of reasons. These reasons underscore whether unfairness to the defendant should prohibit a retrial or not.
Retrials After a Hung Jury
Most of the time, the ban against double jeopardy will not apply after a judge has accepted that the jury is deadlocked (“hung”) and has declared a mistrial—meaning the prosecutor can retry the defendant. A hung jury often meets the definition of manifest necessity, as it’s not a situation where the prosecution’s actions caused a mistrial.
Retrials Due to Prosecutorial Misconduct
Although the majority of prosecutors abide by the rules of court and evidence, a handful push the envelope when it comes to courtroom behavior and tactics. In such cases, a defendant may demand a mistrial. When the defense asks for a mistrial, it’s considered to have waived (given up) the protections against double jeopardy, even when the prosecutor has engaged in intentional misconduct. In this situation, the prosecution can retry the case.
However, if the prosecutor provoked a mistrial by engaging in extreme misconduct (basically forcing the defendant to demand a mistrial), the judge might consider this harassment and decide against allowing a retrial.
Retrials Due to “Manifest Necessity”
Finally, judges sometimes declare a mistrial due to circumstances that have nothing to do with the inability of the jury to reach a decision or the prosecutor’s behavior. For example, if external circumstances resulted in too few jurors left to hear the case, a mistrial would be in order. In these situations, the ban against double jeopardy does not protect the defendant from a retrial.
Will the Prosecutor Retry a Case After a Mistrial?
Just because a prosecutor can retry a case doesn’t mean it will. It takes considerable resources to retry a case, and the prosecution might rather negotiate a plea deal or even dismiss the case. The prosecutor must reevaluate its case, resources, and strategies. Sometimes knowing what cards the defendant will play can make a retrial desirable. Other times, a prosecutor might not want to risk the uncertainties of another trial.
A retrial also comes at the expense of the defendant in terms of time, money, and stress. Defendants who go to trial have to live with the uncertainty of waiting for a verdict of guilty or not guilty. Prosecutors might leverage this uncertainty in their plea negotiations and avoid a retrial.
How Many Times Can a Case End in a Mistrial?
There's no clear legal limit as to how many times a case can be retried following repeat mistrials. But the practical implications—time, expense, and uncertainty to the parties, the court, and the public—generally result in one retrial and no more. For serious or violent offenses, such as murder, violent sex crimes, or a large drug trafficking or anti-trust scheme, the prosecution might pursue a third trial.
In most instances, the judge cannot step in and override the prosecution’s decision to retry a case multiple times. It’s the prosecution’s case, not the judge’s. So unless there’s evidence of misconduct by the prosecution or prejudice to the defendant, the court must allow the prosecution to retry the case. (U.S. v. Wright, 913 F.3d 364 (3d Cir. 2019).)