Ladies and Gentlemen of the Jury, Please Wake Up!

“From time immemorial, jurors have been falling asleep because from time immemorial, lawyers have been boring,” says John Gleeson, who was a federal judge in Brooklyn for 22 years. “We’re the dullest people in the world, for Christ’s sake.”

In a typical criminal trial, 12 jurors in a boxed area listen for hours at a time to testimony, with a few breaks and a lunch hour. Some trials last several months.

“Every lawyer thinks they’re saying the most interesting thing anybody could ever hear,” says Mr. Gleeson, now a partner at Debevoise & Plimpton LLP. But trial testimony, he says, can be “deadly boring.”

Jury consultants say the ennui is exacerbated by shrinking attention spans of the smartphone era.

During jury selection, the judge and lawyers interview prospective jurors to find biases, including questions about hobbies, news sources and other topics.

Lawyers say they watch for prospects already napping during jury selection.

When lawyers see a slumbering juror, “it is a total blow to the ego,” says Sarah Coyne, a former federal prosecutor and now a partner at Weil Gotshal & Manges LLP.

There are no concrete rules for when a judge should dismiss a juror for sleeping. Lawyers say it depends how long they were napping and whether they snoozed through crucial testimony.

In one current trial, Manhattan federal prosecutors are seeking to convince a jury that a Turkish banker is guilty of helping Iran evade U.S. sanctions. The testimony has focused on emails, spreadsheets and wiretapped calls—mostly in Turkish and translated by a live interpreter.

The alleged scheme is so complex prosecutors asked one witness to draw the banks and front companies involved on a large sheet of paper. By the end, the witness had drawn a maze of boxes connected by multicolored lines and arrows to indicate the money flow.

One juror was visibly asleep throughout the first week, his head propped in his hand or rolled into his chest. Occasionally, he awoke to sip water or jot notes before resuming his nap. His eyes were closed during much of the government’s most important witness testimony.

Late last week, U.S. District Judge Richard Berman dismissed the juror, telling the court he was “really sound asleep…not just dozing.”

Judge Berman said when the juror was asked during jury selection what he did in his spare time, the juror said sleep. “He seemed like a very nice fellow,” Judge Berman added.

Judge Berman declined to comment further on the dismissal.

In Brooklyn federal court last week, U.S. District Judge Pamela Chen addressed a somnolent juror in the trial of three former South American soccer officials accused of corruption.

“And as I am speaking to you, you are yawning,” Judge Chen said, telling the juror that he seemed to be asleep and struggling to stay alert.

The juror collected his backpack, beanie and glasses and was excused.

A clerk for Judge Chen said she doesn’t comment on active trials.

The Sixth Amendment guarantees the right to a speedy trial before an impartial jury. American colonists adopted the centuries-old English concept of using laypeople to determine guilt or innocence, partly because colonists trusted fellow citizens more than they trusted British judges, says Valerie Hans, a Cornell Law School professor who studies juries.

To keep jurors attentive, Ms. Hans says, more courts could allow jurors to take notes during testimony—a practice some states previously banned because judges thought note-taking was distracting.

Veteran attorneys have strategies to combat lethargy: Ask the judge to take a break before an important witness; place less-exciting testimony in the morning, not during the post-lunch food coma; walk close to the jury box and speak loudly.

Judges may make eye contact with a juror next to a sleeper and motion to elbow that person awake.

The government and defense are generally careful not to call out a sleeper in open court, to avoid embarrassment and turning the juror against one side.

Former prosecutors say jurors may suffer shock when sitting through a trial for the first time and realizing it is much slower paced than trials on shows such as “Law & Order.”

“On a murder case, if you have 150 pieces of evidence, you have to put an officer on the stand” to testify about each one, says Vincent Cohen, a Dechert LLP partner who was once acting U.S. attorney in the District of Columbia. “They don’t show that on TV.”

A sleeping juror is often viewed as negative for the prosecution, because the government has the burden to prove the defendant’s guilt beyond reasonable doubt.

“If you’re a criminal-defense lawyer,” says Joshua Dubin, a New York jury consultant and defense lawyer, “you pray the jurors fall asleep during the government’s case and wake up during the cross-examination.”

The situation gets particularly awkward if a judge falls asleep. “Everybody knows, so you just keep going,” says Steven Feldman, a former federal prosecutor now working at Murphy & McGonigle. “When you really need the judge, you say ‘objection’ really loudly, so the judge comes awake.”

Sometimes, there’s reasonable doubt a closed-eyed juror is asleep. During a recent retrial in Palm Beach County, Fla., defense lawyers alleged in court filings that a juror slept through critical testimony. After the guilty verdict, they asked Judge Glenn Kelley to order a new trial.

Judge Kelley said in court he saw the juror was closing her eyes while still moving her hands and thumbs—a sign she was awake. (A court manager says the court prohibits judges from commenting to reporters on open cases.)

“She has always been paying attention,” Judge Kelley said, and denied the motion.