All the cases were identified in an internal review by the city prosecutor's office as involving one of four faulty Breathalyzer machines.
Even before the district attorney's announcement, Municipal Court President Judge Marsha H. Neifield had begun hearings to field petitions for new trials.
The Wednesday-morning hearings began April 27 and will continue Wednesdays at 11 a.m. in Courtroom 406 of the Criminal Justice Center, 13th and Filbert Streets.
Tasha Jamerson, spokeswoman for the District Attorney's Office, said that as of early this week, about 20 people had requested new trials and five had been granted.
A new trial does not necessarily mean acquittal. Even without Breathalyzer results, a prosecutor may have the arresting officer testify about a driver's "general impairment" - unsteady gait, slurred speech, a strong odor of alcohol on the breath - that could support conviction.
Jamerson said it was not possible to estimate the cost of the retrials, although they will certainly swell the docket of Municipal Court cases in the near term.
Joseph Kelly, a Port Richmond defense attorney who specializes in DUI cases and one of the first lawyers to challenge the police machines, said new-trial requests have had a positive response by the court.
Kelly said he had filed eight requests and one had been scheduled for retrial.
Bradley Bridge, an assistant Philadelphia public defender involved with the review of city DUI cases involving the faulty Breathalyzers, agreed with the estimate of cases eligible for retrial.
Bridge, however, said he was concerned about the validity of any Breathalyzer testing, especially since his office found a faulty Breathalyzer used at the state police Belmont barracks, whose troopers patrol the Schuylkill Expressway and I-95.
Bridge said the suspect machine at Belmont was used for three months after testing showed it was miscalibrated, from Nov. 24 to Feb. 24.
