Since the 1970s the Hawaii Supreme Court has allowed state judges to decide whether to instruct juries on how to evaluate a witness’s testimony identifying a defendant as the perpetrator.

But since then studies have shown that false identification by witnesses happens more often than previously believed.

A national report last year looked at 250 defendants convicted but later cleared of their crimes; 190 involved eyewitnesses falsely identifying the defendant.

As a result, the state’s highest court took the extraordinary step last month of abandoning its earlier stance.

Misidentification, the court said May 17, is "one of the leading causes of wrongful convictions."

The justices announced a new rule that requires judges to instruct jurors on how to weigh an eyewitness identification when requested by the defense lawyer.

Associate Justice Simeon Acoba suggested that the instruction should have the jury weigh more than a dozen factors, including the opportunity of the witness to observe the offender, the stress, if any, the witness was under and the extent of the witness’s certainty in making the identification.

"It’s long overdue," said state Public Defender Jack Tonaki, who has pushed for new rules that would make giving the instruction mandatory.

City Prosecutor Keith Kane­shiro was far less enthusiastic.

"The judge doing the trial is in the best position to determine whether such instruction should be given," he said in a statement. "The court has effectively taken away the discretion of the trial judge."

The high court heard arguments in the case Feb. 16 on the stage of Farrington High School’s auditorium. The session before high school students was part of the court’s efforts to help the public understand the role of the Judiciary.

In its 55-page decision, the justices said that when asked to give the instruction — and identification is central in the case — trial judges must honor the request.

The ruling is considered significant because it deals with the judge’s instructions to the jury after the evidence is presented. The jury determines the facts of what happened, but in reaching a verdict the jurors must apply the facts to the law given to them in the instructions from the judge.

Although the court adopted the new rule, four of the five justices held that the mandate should not be applied retroactively and upheld Steve Cabag­bag Jr.’s 2010 convictions of second-degree theft and driving a stolen truck.

During the trial, a police officer’s identification of Cabag­bag as the truck’s driver was the key issue. The defense told the jury that the officer did not get a good look at the driver in the early morning darkness.

The jury was not given the witness identification instruction. The jurors found Cabag­bag guilty. He was sentenced to five years’ probation.

Writing on behalf of the justices, Acoba, a Farrington High School graduate, said "a robust body of research" has been conducted since the high court ruled in 1976 that the trial judge can decide whether to give the instruction to the jury.

In addition to the study of the 250 exonerated defendants by University of Virginia law school professor Brandon L. Garrett, Acoba cited other reports that showed identification by witnesses was the key reason for the wrongful convictions.

"Without appropriate instructions from the court, the jury may be left without sufficient guidance on how to assess critical testimony, sometimes the only testimony, that ties a defendant to an offense," Acoba wrote.

"Most significantly, the impetus for a change in our approach lies in the empirical research that reveals that people generally do not understand all of the factors that affect the reliability of an eyewitness identification," he said.

Acoba said courts in several other states, including Kansas, Utah and New Jersey, require trial judges to give the specific jury instruction.

Chief Justice Mark Reck­ten­wald wrote another part of the opinion that upheld Cabag­bag’s conviction. Reck­ten­wald made clear that the rule would apply only to future cases and that the identification instruction did not have to be given in Cabag­bag’s case.

Associate Justices Paula Naka­yama, James Duffy and Sabrina McKenna agreed with the chief justice.

Recktenwald wrote that the "jury’s attention was adequately drawn to the eyewitness identification issue" by the arguments from the prosecution and defense, the cross-examination of prosecution witnesses and the court’s general jury instructions.

Acoba dissented, saying the instruction should have been given in Cabag­bag’s case. He said he would have ordered a new trial.

"Although we’re disappointed that the case itself wasn’t reversed, we are very happy and pleased with the outcome in terms of the requirement," Tonaki said.

He said some trial judges here give the eyewitness jury instruction, but the majority do not.

If the justices had gone along with Acoba’s dissent and held that the instruction should have been imposed retroactively, the decision could have led to challenges to dozens of other convictions, Tonaki said.

Tonaki, who argued the Cabag­bag case for the defense, said the ruling does not resolve what he sees as other problems involving witness misidentification of defendants.

Another major issue, he said, is the way police conduct photo lineups by letting a witness view all the photos at once rather than sequentially.

"I told the Supreme Court in oral arguments that the case is not the end-all or solve-all," he said.