Can a defendant's mistrial motion waive double jeopardy protection in Utah? State v. Cooper Explained

In State v. Cooper, the Utah Court of Appeals examined whether a defendant who requests a mistrial can later claim double jeopardy protection against retrial. The case provides important guidance on the intersection of double jeopardy rights and ineffective assistance of counsel claims.

Background and Facts

Cooper was charged with rape, forcible sodomy, and aggravated sexual assault. During his first trial, the victim testified on cross-examination that she had never promised to drop charges if Cooper paid her medical expenses. Defense counsel then sought to introduce text messages from the victim contradicting this testimony, but the State objected because the messages had not been produced in discovery. When the trial court excluded the text messages, both the State and defense counsel moved for a mistrial—the State citing prejudice, and defense counsel claiming his own ineffective assistance.

Key Legal Issues

The court addressed two primary questions: whether Cooper’s retrial was barred by double jeopardy protections, and whether his second trial counsel provided ineffective assistance by failing to raise a double jeopardy defense or call certain witnesses.

Court’s Analysis and Holding

The Court of Appeals ruled that Cooper waived any double jeopardy protection by requesting a mistrial himself. The court emphasized that “a motion by the defendant for mistrial is ordinarily assumed to remove any barrier to reprosecution.” Additionally, the court found manifest necessity existed for the mistrial, as defense counsel’s discovery violation created an impossible situation requiring judicial intervention. Regarding the ineffective assistance claim, the court held that counsel cannot be ineffective for failing to file a futile motion that would have been properly denied.

Practice Implications

This decision highlights the strategic complexity of mistrial requests. Defense attorneys must carefully weigh whether requesting a mistrial effectively waives constitutional protections that might otherwise bar retrial. The case also demonstrates that discovery compliance remains critical—violations can create situations necessitating mistrials that ultimately harm the defendant’s position.