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Breathalyzer source code must be disclosed

Florida police can't use breathalyzers unless the source code can be reviewed, a state court decides.

Declan McCullagh Former Senior Writer
Declan McCullagh is the chief political correspondent for CNET. You can e-mail him or follow him on Twitter as declanm. Declan previously was a reporter for Time and the Washington bureau chief for Wired and wrote the Taking Liberties section and Other People's Money column for CBS News' Web site.
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Declan McCullagh
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Florida police can't use electronic breathalyzers as courtroom evidence against drivers unless the innards are disclosed, a state court ruled Wednesday.

A three-judge panel in Sarasota County said that a defense expert must have access to the source code--the secret step-by-step software instructions--used by the Intoxilyzer 5000. It's a simple computer with 168KB of RAM (random access memory) that's manufactured by CMI of Owensboro, Ky.

"Unless the defense can see how the breathalyzer works," the judges wrote, the device amounts to "nothing more than a 'mystical machine' used to establish an accused's guilt."

The case, one of the first to test whether source code used in such devices will be divulged, could influence the outcome of hundreds of drunk-driving prosecutions in the state. So far, Florida courts have been split on the topic, with some tossing out cases involving breath alcohol tests and others concluding that the information about the machine's workings should remain a trade secret.

In one similar 1988 case, Florida defense attorneys discovered that the police had mechanically modified a breath test machine so much that its results were no longer valid and could not be admitted as evidence in a prosecution.

The Sarasota judges didn't require the public disclosure of the source code. Rather, they ordered that it must be given to a defense expert who will keep it in confidence and return it when his analysis is complete. That analysis could show bugs or reveal that the code was modified after the Intoxilyzer was certified for use by the state--meaning the device's output could not be used in court.