Posted Mar 06, 2012 09:12 pm CST
When police in San Francisco’s traffic division stop a motorist on suspicion of drunken driving, one of the first steps they take during a field sobriety test is to check the individual’s blood alcohol level on a portable device to determine whether it exceeds 0.08 limit.
The devices are supposed to be checked every 10 days or after 150 tests, to be sure they are correctly calibrated. But after a couple of public defenders noticed in January that police logbooks of tests conducted on the devices were suspiciously accurate all the time, officials looked into the matter further.
It now appears that up to 1,000 convictions could be thrown out in drunken-driving cases dating back to 2006, because the devices weren’t regularly tested as protocol required, the San Francisco Chronicle reports.
The problem is that claimed calibration tests uniformly showing accurate readings of 0.082 on the devices’ gas canisters couldn’t be true, officials explained at a press conference yesterday, because the devices sometimes get out of whack.
“It would be mathematically impossible for that to occur,” said Public Defender Jeff Adachi of the entirely accurate calibration test readings logged by police. Hence, “the results that we have here plainly show that the accuracy testing was not being done.”
His office and the district attorney’s office are working together to determine what convictions may need to be revisited over the testing issue. Meanwhile, the police department is conducting an internal investigation with which the traffic division is cooperating.
Further blood-alcohol testing is conducted at the police station after suspects are arrested in drunken-driving cases, and the accuracy of those tests isn’t being questioned.
Hat tip: Reuters.