Zachary Sevigny was slashed with a box cutter by a stranger outside a convenience store in 2011.
Neither Sevigny nor his friend identified Jeremy Gomes as the attacker when shown his picture in a police photo array. But a week later, they saw Gomes inside a Pittsfield gas station and told police he was the culprit.
Gomes was found guilty of the attack, but his lawyer is challenging his conviction based on what he says were unreliable eyewitness identifications.
That challenge is one of four cases seeking changes in the way eyewitness identification testimony is presented to juries. The cases are set to be heard by the highest court in Massachusetts next month. Defense attorneys are pushing the court to adopt stronger instructions to advise jurors that eyewitness identifications are not always reliable.
Specifically, they want judges to tell juries that human memory is easily influenced and not like a video recording. They also want juries to be warned that witnesses who appear highly confident about their identification are not therefore necessarily reliable. And they want juries told that the failure to identify a suspect in an identification procedure — such as a police lineup or photo array — may reduce the reliability of a later identification of the same suspect by the witness.
Gomes’s attorney, John Fennel, said jurors need to hear from judges about the fallibility of eyewitness identification, even by crime victims who strongly believe they are identifying the right person.
‘‘These are people who had something terrible happen to them. They are people of good will trying to do the best they can, but what the science tells us is that people of good will are just wrong about this a lot,’’ Fennel said.
The Massachusetts cases have drawn the attention of groups that have long questioned the reliability of eyewitness testimony, including the Innocence Network, the American Psychological Association, and the Center for Law, Brain, and Behavior. Each group has filed a legal brief supporting more cautionary instructions from judges on eyewitness identification.
The Innocence Network argues that judges too often admit, and juries too often accept, unreliable eyewitness identifications, which are the leading cause of wrongful convictions. The American Psychological Association cites a study showing as many as 40 percent of witnesses who made positive identifications were mistaken despite describing themselves as 90 percent to 100 percent confident in their identifications.
But prosecutors say defense attorneys are given ample opportunity to challenge witness identifications. In the Gomes case, his attorney received permission from the judge to call an expert witness to testify about eyewitness identification, but did not. Gomes’s attorney pointed out during cross-examination that only one witness — the store clerk — identified Gomes in a photo lineup and that several descriptions given by witnesses did not match Gomes.
The standard Massachusetts jury instructions used by the judge include a warning that witnesses can be ‘‘honest but mistaken.’’
Berkshire District Attorney David Capeless said challenges to eyewitness identification should be presented to the jury through expert witnesses, not instructions from the judge.
Suffolk University Law professor Rosanna Cavallaro said the push for changes in jury instructions has gained support in recent years because of generally accepted scientific studies about the malleability of memory and the number of wrongful convictions blamed on mistaken witness identifications.
‘‘For many years, it was considered the gold standard of a trial — the best thing you could have was a witness on the stand who said, ‘I’m sure that’s the guy,’ ’’ said Cavallaro, a member of a study group appointed by the Massachusetts Supreme Judicial Court that concluded that the state’s current jury instructions on eyewitness identification are inadequate.
‘‘Recently, we’ve become very skeptical of that,’’ she said. ‘‘We know that memory is much more complex than we actually thought it was.’’
The Supreme Judicial Court is scheduled to hear the cases Sept. 8.