The Supreme Court declined Wednesday to extend constitutional safeguards against the use of some eyewitness testimony at criminal trials, despite concerns that eyewitness identification plays a key role in innocent people going to prison.

In a case dealing with a narrow slice of the issue of identifying a suspect, the court voted 8-1 to uphold the theft conviction of Barion Perry in New Hampshire state court. Perry argued that courts should be able to exclude eyewitness testimony when identifications are made under suggestive circumstances, even when there is no evidence of manipulation by the police.

Judges already can bar testimony when the police do something to influence a witness to identify a suspect.

Justice Ruth Bader Ginsburg said in her opinion for the court that in cases with no police misconduct, lawyers can cross-examine a witness and juries can weigh the reliability of the testimony.

Ginsburg said a prime reason for excluding such testimony when the police are involved is deterrence. "Where there is no improper police conduct, there is nothing to deter," she said.