When to declare a mistrial is not always a clear cut decision.

Mistrials inevitably raise the prospect that double jeopardy may prevent a second trial.  If the motion for a mistrial is made by the defense, many appellate courts find the defense waived a double jeopardy claim.  When the motion is made for a mistrial by the prosecution, there is real risk that double jeopardy will prevent a second trial.

There are two important caveats:  first, the double jeopardy clause of the United States Constitution is not a mere technicality.  It is a fundamental feature of the American legal system.  Second, being consciously aware that manifest necessity is the current standard for finding a mistrial can permissively allow a second trial.  The judge died during trial….one of the lawyers had a heart attack….are pretty easy to understand.  The ABA Journal’s recent report illustrates the stakes in these decisions:

The Georgia Supreme Court on Monday ruled that an accused killer can’t be retried because the trial judge mistakenly declared a mistrial after the defense gave its opening statement.

The court said that requiring the defendant, Geary Otis, to be retried would violate the ban on double jeopardy, reported the Associated Press, the Fulton County Daily Report (sub. req.) and AJC.com.

At a news conference on Tuesday, family members of the murder victim joined with Atlanta’s mayor and the Fulton County district attorney to urge the supreme court to reconsider its opinion, according to the Fulton County Daily Report.

“We can’t let Geary Otis get away with this,” said Atlanta Mayor Kasim Reed, who practiced law before taking office. “Would you want a technical error to allow someone who stabbed your loved one to walk away without consequences?”

Otis was accused of attacking two residents of an independent living facility with a knife in June 2013, killing a 75-year-old woman and injuring a 71-year-old man. Police had to use a stun gun to subdue Otis, who was 64 at the time.

During opening arguments in Otis’ April 2014 trial, his defense lawyer argued her client had “just snapped” and asked jurors to consider that mental illness comes in many forms. Prosecutors objected because the defense had not given notice of an insanity defense. The defense lawyer said no notice was required because she intended to rely on the testimony of lay witnesses rather than independent experts.

Judge Ural Glanville declared a mistrial over the defense lawyer’s objections and rescheduled a new trial to begin in two weeks.

The Georgia Supreme Court said the defense lawyer was right. Notice of an insanity defense is required only when expert testimony will be offered, the court said.

When a mistrial is improperly declared over the protest of the defense, the accused cannot be retried, the court said.