The disturbing case of wrongly convicted Army Sgt. Dennis Maher ["Three Strikes," editorial, April 6] highlights one of the criminal justice system's best-kept secrets: Eyewitnesses frequently identify innocent people as the perpetrators of crimes.

A recent study of cases in which convictions of innocent people were overturned on the basis of DNA evidence found that mistaken eyewitness identifications were the primary cause of most false convictions. Unfortunately, because not every case involves evidence that can be tested for DNA and because not every defendant can afford DNA testing, scores of innocent men and women may remain in prison.

For several decades, researchers studying eyewitness identifications have advocated reforms that would improve the reliability of identification procedures. For example, studies have shown that identification procedures yield more accurate results when witnesses view potential suspects one at a time rather than in a group, and when the police officer running the identification procedure does not know who the suspect is.

In addition, expert witnesses who can explain factors that may undermine the reliability of an identification in a particular case allow juries to make more informed evaluations of which eyewitnesses to believe.

California, Georgia and Ohio courts permit the testimony of experts on eyewitness testimony, while New Jersey has adopted broad changes in the way its police officers conduct identification procedures. Despite the fear expressed in The Post's editorial, these reforms have not "paralyzed" prosecutors.

Until the criminal justice system makes a serious effort to address the problems that eyewitness testimony so often creates, our prisons will continue to house men and women who are every bit as innocent as Sgt. Maher.

RONALD S. SULLIVAN JR.

Director, Public Defender Service

District of Columbia

Washington