When Lynne M. Abraham was Philadelphia's district attorney, her office maintained a list of city police officers banned from testifying in court because their credibility had been tainted, according to a police arbitration report.

The Internal Affairs unit had investigated the conduct of at least some of those officers, devaluing them as witnesses. In certain instances when they were not allowed to testify, cases were discharged, according to a report made public last week.

The existence of such a list has been a closely guarded secret in court and police circles. It was not known whether District Attorney Seth Williams, who took over from Abraham in January, maintains such a list. His spokeswoman did not return telephone calls Saturday seeking comment.

Abraham confirmed Saturday that, under her direct supervision, prosecutors had not allowed officers deemed untrustworthy to testify. She said that she did not know of the existence of a list and that the policy had applied to a "relatively small number of officers."

"It's not about numbers," she said. "It's about being a thoughtful and honorable prosecutor who's not interested in numbers, just in justice."

Rather than circulating a list, Abraham said, "we would notify the various police divisions that we wouldn't use Police Officer X" to testify.

Abraham said she did not know whether criminal cases had been dismissed and criminals walked free because prosecutors would not use certain officers' testimony.

"I can't say that [the policy] did or it didn't" affect the outcome of cases, she said.

But often, she added, other officers who were at the scene of a crime could appear in court instead of the tainted officer.

Abraham's comments came in response to a 24-page report, publicly released last week but issued in 2006, that details how the district attorney barred two officers from testifying about arrests they had made.

Court of Common Pleas Judge Paul P. Panepinto released the report after a legal fight by the Philadelphia Daily News. It provides findings in one of about 200 arbitration cases being made available to the Daily News and The Inquirer under Pennsylvania's Right to Know Act.

The release of the decisions from the arbitration hearings - courtlike sessions dealing with disputes between police officers and their superiors - was opposed by Lodge 5 of the Fraternal Order of Police, the city police union, which argued that publication of the decisions could damage the officers' reputations.

The arbitration case that revealed the no-testimony list involved two officers, Norma I. Vazquez and Darryl L. Braxton, who had been placed on desk duty by police brass because the District Attorney's Office made it clear it would not prosecute their cases.

The District Attorney's Office's concern with Vazquez and Braxton stemmed from an Internal Affairs investigation after they were involved in the arrest of a woman whom they believed to be a prostitute but who was an undercover police officer.

Vazquez and Braxton were reprimanded after a long investigation. A superior officer said that they had learned their lessons, and that training would address their misconceptions about when they could arrest a person.

But prosecutors argued that the officers' credibility "could not be vouched for," and that prosecutors would not be able to obtain convictions based on the officers' testimony, the report said. The information about the officers' blemished record would have to be turned over to defense teams, prosecutors argued, and would be used to blow holes in their cases.

The FOP complained that banning Vazquez and Braxton from testifying was an abuse of power by the District Attorney's Office.

In an unspecified number of cases involving the two officers, according to the report, criminal complaints had to be dismissed because the officers were not allowed to testify. Even if the officers had witnessed a homicide, the report said, it was unclear if the prosecutors would allow their testimony.

Aware that the officers' arrests might not be prosecuted, the Police Department eventually reassigned the officers to desk duty, answering phones.

Ira F. Jaffe, the arbitrator, called the prosecutors' use of the list a "broad and unreviewable power" that could be misused. He ordered that Vazquez and Braxton be returned to street duty and be compensated for lost overtime as a result of being on desk duty.

In finding for the officers, Jaffe acknowledged the awkward "catch-22" that was being created.

"The situation of having the grievants on the street making arrests while the D.A. Office then declines to prosecute those arrests is plainly not a satisfactory one," he wrote.

Contact staff writer Robert Moran at 215-854-5983 or bmoran@phillynews.com.