Scores of DUI convictions in San Francisco are now being called into question because of potentially negligent work by police testing devices used to measure blood alcohol levels, the city's district attorney and public defender announced in a rare joint news conference Monday.
San Francisco District Attorney George Gascon and Public Defender Jeff Adachi Monday morning announced the investigation into cases dating back as far as 2006 where preliminary alcohol screening devices were used by officers arresting a suspect for driving under the influence.
Police failed to conduct accuracy tests on the Alco Sensor IV, a handheld device used to measure someone's blood alcohol content while out at the scene of a traffic stop, Adachi said.
According to the Police Department's manual and the device's manufacturer guide, officers are required to check the devices for accuracy every 10 days using a known sample from a gas canister.
But in logs where the officers reported the data, the samples and the readings on the device always read 0.082, according to Adachi, who called the consistent exact matches "mathematically impossible."
The public defender's office notified the district attorney's office, which immediately withdrew the use of the devices as evidence in its ongoing DUI cases, Gascon said.
He said he talked to police officials and learned that the department had not been following the manufacturer's guide.
The department has since discontinued the use of its 20 devices, Gascon said.
Adachi says his office, which handles between 500 and 1,000 DUI cases per year, will seek to have tossed any pending cases involving the devices as well as try to overturn previous convictions and seek restitution for increased insurance rates or other penalties that might have been
incurred as a result.
Gascon emphasized that the devices are "a piece of a multi-pronged approach" to prosecuting the cases, which also usually involve field sobriety tests and blood tests.
He added that the investigation does not count cases investigated by an agency other than the Police Department, such as the California Highway Patrol.
A police spokesperson was not immediately available to comment on the allegations.