A white woman witnesses a mugging on a city street and later testifies against a black defendant in court. Her testimony is the crux of the prosecution's case.
How should the jury view her eyewitness account?
In New Jersey, judges in certain cases must now instruct jurors to take into account the race of witnesses and defendants when deciding their verdicts. Research shows members of one race may have trouble identifying someone of another race, judges will tell them.
A state supreme court ruling last month makes New Jersey the second state in the US to officially recognize the likelihood of misidentification due to cross-race bias. (California is the first.) The decision is stirring heated debate over whether such a remedy only entrenches racist attitudes - or actually creates protections against racial bias in the nation's judicial system.
"Eyewitness testimony is very effective if you're dealing with somebody you know. But if you're dealing with strangers, especially strangers of another race, and if that's the only data you have to go on ... it could be suspect," says Jerry Bruce, chairman of the Psychology Department at Sam Houston University in Huntsville, Texas.
This possibility of misidentification, called cross- or own-race bias, has been studied by psychologists and sociologists for years, as have other factors prevalent in eyewitness identification.
"There's pretty good evidence for the fact that different races develop different cues for reading people," says Stephan Landsman, professor of law at DePaul University in Chicago.
In a 1997 study, for example, Dr. Bruce found that white women made more errors recognizing African-American faces than they did with white faces.
The issue is routinely raised by lawyers across the country. In most courts, expert witnesses are brought forward to talk about the issue, and lawyers can cross-examine and challenge the research.
But New Jersey has taken it a step further, since a judge's instruction is the last thing the jury hears before it deliberates.
The instruction applies in only a small number of trials: mixed-race criminal cases where there is no other evidence (such as DNA or fingerprints) to corroborate an eyewitness account.
Jurors should know if race might be distorting a witness's perception, supporters of the mandate say.
But it's the principle that counts for Simon Rosenbach, an assistant prosecutor for Middlesex County, N.J., who argued against the mandate in court. The ruling is "an awful idea," he says, because it is unfair to say that race in and of itself could be cause to doubt a witness.
"It doesn't say 'Consider my life experience,' it says, 'Consider my race,' " says Mr. Rosenbach. What if, for example, a white witness had been raised in Africa and had practice differentiating black individuals? "You're saddling one individual with the traits of an entire race," he adds.
But others see the high court's ruling as appropriate.
"Our eyes can sometimes see what our mind wants us to see," says N. Lee Cooper, former president of the American Bar Association and a trial lawyer in Birmingham, Ala.
Race is just one potentially problematic factor among many, from lighting at the time of the crime to the level of violence, says Jim Neuhard, director of the Michigan Appellate Defender's Office. But despite that potential, eyewitness identification is powerful in a jury trial, he says.
And bias is not just a black-white issue, Mr. Neuhard emphasizes. "You can pose the same issues for other races or ethnic groups - Arabs, Jews, [Asians], African-Americans, and you sometimes find stereotyping and lumping people together."
There may be an added benefit in the states that alert juries to the problem, Professor Landsman notes. Perhaps this will "encourage prosecutors to find more evidence" in cases where the witnesses may not be reliable.