A large number of recent DUI convictions in San Francisco are now being called into question because of the way police tested devices used to measure the blood alcohol level of suspected drunk drivers.

San Francisco District Attorney George Gascon and Public Defender Jeff Adachi said that investigations into cases dates back as far as 2006, where preliminary alcohol screening devices were used by officers in the field to test driver’s blood alcohol level.

According to the investigation, police failed to conduct proper accuracy tests on the Alco Sensor IV, the handheld device used to measure blood alcohol content while at the scene of a traffic stop.

The manufacturer’s guide states that officers are required to check the devices for accuracy every 10 days using a known sample. But police logs showed that the samples and readings on the devices always read 0.082.  When notified of the problem, the department discontinued the use of its 20 devices.

Adachi said his office is looking to have any pending cases involving the devices tossed. He also said he will work to overturn previous convictions and seek restitution for cases that involved the Alco Sensor IV.

The San Francisco Police Department is cooperating with the investigation.



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