Police Blotter: Bid for breathalyzer code denied

A Minnesota man convicted of drunk driving did not have the right to inspect the programming of a police breathalyzer, a state appeals court has ruled.

The Minnesota Court of Appeals last week rejected Michael Garberg's claim that he was entitled to obtain the source code to the Intoxilyzer 5000EN.

Garberg failed to convince the court that obtaining the source code "may relate to his guilt or innocence," wrote Judge Heidi Schellhas.

After Garberg was stopped for speeding one evening in October 2008, he was given an Intoxilyzer test that reported an alcohol concentration of .24, over the state maximum of .08. In Minnesota, refusing to take an alcohol test is a crime.

A trial judge rejected Garberg's request for the Intoxilyzer source code, and he was convicted of a third-degree driving while impaired, a misdemeanor.

The Intoxilyzer 5000EN, manufactured by CMI of Owensboro, Ky., uses a primitive computer with 56KB of of programmable read-only memory and 40KB of RAM. The system produces a printout with the date and time, the Intoxilyzer serial number, and the results of the test. It can be connected to a modem for remote access; although CMI claims it uses a "technique of slope detection" to calculate the beginning and end of a single breath, no additional information is publicly available.

As more and more defense attorneys--especially in Minnesota--have questioned the reliability and accuracy of CMI's code, judges have wrestled with the circumstances under which the source code should be disclosed. CMI has resisted releasing the complete, unredacted original source code in electronic form.

In April 2009, the Minnesota Supreme Court ruled that, at least in situations where the source code has been proven to be necessary to evaluate the Intoxilyzer's results, DUI defendants should be able to have access to it. That ruling said that "an analysis of the source code may reveal deficiencies that could challenge the reliability of the Intoxilyzer."

Police Blotter has returned to this topic frequently, including an August 2007 Minnesota ruling favoring a defendant, a February 2009 one that didn't, and an October 2005 dispute in Florida.

Excerpts from Tuesday's ruling:
Appellant argues that the source code was relevant, that the state had possession or control of the source code and, for the first time on appeal, that due process requires disclosure of the source code. The state opposes all of appellant's arguments and also argues that appellant presents a "general challenge to the validity" of the Intoxilyzer 5000EN software, which was approved in a rule-making process.

We begin by rejecting the state's argument that the district court had no jurisdiction to hear a challenge to the validity of the Intoxilyzer 5000EN software. Appellant challenges the Intoxilyzer test results in his case; he has not presented a challenge to the use of the Intoxilyzer in general. A defendant charged with DWI may challenge his Intoxilyzer test results in his criminal case.

Appellant argues that his discovery motion sought relevant evidence because the source code is relevant. The district court's lack of findings or rationale makes review difficult. But, in this case, rather than remand for findings, we affirm the district court because appellant submitted no evidence in support of his discovery motion. Appellant failed to make a threshold evidentiary showing that the source code information may relate to his guilt or innocence, negate his guilt, or reduce his culpability.

We therefore do not reach appellant's arguments regarding possession or control of the source code. We also do not reach appellant's due-process argument, which appellant waived because he did not raise it in district court.

Police Blotter is Declan McCullagh's regular CNET report on the intersection of technology and the law.