(CBS News) Hundreds of drunk-driving convictions in San Francisco could be tossed out as a result of potentially incorrect breathalyzer test results.
Police in San Francisco are now being accused of gathering as many as 1,000 potentially faulty blood alcohol readings over a span of 10 years because they did not properly maintain and calibrate their 20 breath analyzer machines, commonly known as breathalyzers.
Jeff Adachi, a San Francisco public defender, told CBS News, "What we learned is that the police department was not testing these devices for accuracy. ... They're supposed to test these devices every 10 days and that wasn't happening."
Attorney Peter Fitzpatrick discovered the problem when his client took two breath tests an hour apart with very different results. He said there was a five-point difference in his client's readings. "(It's) a huge discrepancy that no criminalist would ever say is reasonable," Fitzpatrick said.
When people drink, alcohol is absorbed in the blood and carried through the brain to the liver and heart before diffusing in the lungs. There it is exhaled in our breath and detected by the breathalyzer machine. But the results are only as accurate as the technology.
Trent Copeland, CBS News legal analyst, said, "When the equipment fails, when the computer-generated technology simply isn't maintained properly, then suddenly the whole system is thrown into chaos and we can't rely on anything in terms of the results."
Drunk-driving convictions are serious. You can lose your license, your job, and spend time in jail. Now hundreds of people may get a DUI do-over.
While the police department conducts its own investigation, the San Francisco Public Defender's Office and the district attorney are reviewing cases to determine if any drivers were wrongfully convicted by the faulty data.
San Francisco District Attorney George Gascon said in a press conference that the information gathered points to negligence - not intentional criminal conduct.
In the meantime, all 20 of the department's breath test machines have been pulled off the street.
CBS News legal analyst Jack Ford said on "CBS This Morning" not every conviction will be reconsidered going forward - only the ones where people were convicted solely on the police's initial test.
Ford explained, "The machines that are problematic here are (used for) pre-screening ... the ones that the police officers use out on the street. So it's part of the first look at whether or not you should be held responsible.
"Most of the DUI cases out there, they go back to headquarters and then there's another test, either the traditional breathalyzer or even a blood test. So anybody who was found being over the limit based upon those two, you know, they won't get away with it. It's cases where it was based solely on this early testing out on the street that we're going to see ... hundreds of these cases apparently are going to go away."
This case, Ford said, will likely make other police departments across the U.S. re-evaluate their systems.
But this case may end up having bigger consequences, Ford said. "If it was negligence and everybody thought somebody else was doing testing and they were relying on it, that's one thing," he said. "But if people in the department knew the testing wasn't being done and they were still convicting people based upon that, you could have a lot more to the story. You could have a criminal investigation, official misconduct or on the federal level, you might have civil rights violations. There could be a lot more to this."
To watch Ben Tracy's full report and Jack Ford's entire discussion on "CBS This Morning," including talk about what technology means for law enforcement and justice, watch the video in the player above.