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Police blotter: Closed-source breathalyzer on trial

In this installment: Should computers with secret methods of operation be used to convict Americans accused of drunk driving?

"Police blotter" is a weekly report on the intersection of technology and the law. This episode: Should computers with secret methods of operation be used to convict Americans accused of drunk driving?

What: A dispute in Sarasota County, Fla., involving whether defendants accused of drunk driving should have the right to examine the innards of a portable "Intoxilyzer" computer used by police.

When: A hearing is scheduled before five county judges on Friday.

Who: Robert Harrison, an attorney in Venice, Fla., says he will ask the court to divulge the source code to the Intoxilyzer.

Background: The outcomes of hundreds of drunk-driving prosecutions in Florida are up in the air because of a dispute over whether defendants should be entitled to review the inner workings of the machines used to do breath tests.

Defense attorneys say their clients should have the right to inspect the source code to breathalyzers that were once certified for police use but subsequently changed without re-certification.

So far, Florida courts have split on the topic, some tossing out cases involving breath-alcohol tests and others concluding that the information about the machine's workings should remain a trade secret. The Intoxilyzer 500, a simple computer that uses 168KB of RAM, is manufactured by CMI of Owensboro, Ky.

The dispute could determine how much flexibility police departments have in modifying breathalyzers after they've been officially certified. But it's unlikely to produce any general requirement that source code be made available for public scrutiny.

An excerpt from one Florida appeals court's opinionaddressed manuals and schematics but not software source code: "When a person risks the loss of driving privileges or perhaps freedom based upon the use and operation of a particular machine, full information includes operating manuals, maintenance manuals and schematics in order to determine whether the machine actually used to determine the extent of a defendant's intoxication is the same unmodified model that was approved pursuant to statutory procedures. It seems to us that one should not have privileges and freedom jeopardized by the results of a mystical machine that is immune from discovery, that inhales breath samples and that produces a report specifying a degree of intoxication."