Breathalyzer machines, housed at police headquarters, are used to obtain the blood-alcohol content of people arrested on suspicion of drunken driving.
When the problem was first made public in March, police and D.A. office officials said one miscalibrated machine and 416 drunken-driving cases was the scope of the blunder. A week later, they revised those numbers to four machines and 1,147 cases.
The final tally of affected cases now is 2,126, and 667 of those individuals are not eligible for new trials because they ultimately were not arrested, were found not guilty at trial or prosecutors dropped the cases, the D.A.'s office said.
On April 27, Philadelphia Municipal Court President Judge Marsha Neifield began hearing requests for new trials from the pool of 1,459 affected defendants who have either already pleaded guilty or were found guilty.
Tasha Jamerson, spokeswoman for the district attorney, said it was too early to determine the cost of retrying the cases because notices are still being mailed to defendants.
As of last week, Neifield had heard 20 requests for new trials, granting five and denying 15, Jamerson said.
A defense attorney first alerted city officials to the bad Breathalyzer readings in late February.
Four of the Police Department's eight machines were spitting out bad readings between September 2009 and November 2010, the investigation concluded.
Police Commissioner Charles Ramsey told reporters on March 23 that the problem boiled down to one officer who was responsible for calibrating the machines. "The error was human error," Ramsey said then. "It is inexcusable, period. Should not have happened."