Police Blotter: Intoxilyzer code must be disclosed

Police Blotter is a weekly News.com report on the intersection of technology and the law.

What: Kentucky man charged with drunken driving asks manufacturer of Breathalyzer-like test for the source code, a request that both the company and the state attorney general claim is unreasonable.

When: Kentucky Court of Appeals rules on January 18.

Outcome: Appeals court reverses ruling of two lower courts, saying the source code for the Intoxilyzer 5000EN must be turned over.

What happened, according to court documents:
For many years, police and prosecutors have told judges that breath tests are able to provide incontrovertible proof that a defendant violated laws against drunken driving.

But now some defendants are fighting back. Police Blotter reported on a Minnesota case last year in which the state supreme court ordered that the source code be revealed. That follows a 2005 DUI prosecution in Florida in which the defense also won the right to inspect the source. In some cases, prosecutors have dropped DUI charges rather than turn over the source code.

The most recent case involves a Kentucky man named Lennie G. House, who was charged with operating a motor vehicle while under the influence of alcohol, with additional penalties for allegedly having an alcohol concentration of 0.18 or higher. House failed a breath test given by the closed-source Intoxilyzer 5000EN, which is manufactured by CMI of Owensboro, Ky., and is one of the most popular alcohol level-testing devices used by police nationwide.

House was charged with DUI on March 8, 2006. Four months later, his attorney requested that prosecutors turn over the source code for the Intoxilyzer 5000EN. When the state attorney general did not comply, the defense attorney sent a subpoena for the source code directly to CMI. Computer source code is, of course, a series of human-readable instructions that are eventually compiled into the object code that a computer executes.

Access to the source code is key. Without it, a Breathalyzer-like device is a black box that can determine a defendant's guilt without being subject to independent scrutiny or evaluation. Inspection of the source code can discover programming mistakes or even intentional skewing.

Both CMI and the state attorney general, Jack Conway, opposed the subpoena for the source code--which led the defense counsel to ask the trial judge to suppress the results of the breath test in their entirety. In September 2006, a trial judge sided with prosecutors, and four months later, a circuit court did too.

House appealed once again, this time to the Kentucky Court of Appeals. By a 2-to-1 margin, the court agreed that requesting the source code--as long as confidentiality procedures were followed--was not unreasonable.

Excerpts from the Court of Appeals of Kentucky's opinion:
A subpoena may be quashed only upon a showing that compliance therewith would be unreasonable or oppressive. We do not believe the commonwealth and CMI have made this showing.

The request is not unreasonable because its purpose is to challenge the validity of the breath alcohol readings produced by the Intoxilyzer 5000 instrument, which is anticipated to be used at trial in support of the Commonwealth's DUI charge against House. The reading was also used to support the aggravating factor of driving with a breath alcohol reading of .18 or more.

Relevant evidence is admissible unless excluded by some other rule. Because a flaw in the computer source code of the Intoxilyzer 5000 would be consequential to the accuracy of the reading intended to be relied upon by the commonwealth, such evidence is relevant and admissible. Accordingly, requesting the computer code to test the verity of the readings produced by the instrument is not unreasonable.

Moreover, the burden upon CMI in producing the code is not oppressive. The record discloses that the code could be copied to a CD-ROM computer disc and produced in that form at minimum expense. It appears that the only other requirement would be that the passwords to access the code would need to be supplied. Thus, the burden of providing the information is minimal, and the expense de minimis.

The commonwealth and CMI argue, however, that the computer code is a protected trade secret and that this should weigh against disclosure. However, House has expressed his willingness for he, his attorney, and his expert witness to enter into a protective order stipulating that the code or its contents are not to be shared with any party outside of the case.

The district court is authorized to enter such orders. We further note that the order may provide that any copies or work product generated as a result of the software engineer's review be returned to CMI upon completion of the review. As civil and/or criminal penalties could result from the disclosure of the code to other parties, such a protective order should obviate any concern CMI may have with respect to protection of its source code.

The commonwealth and CMI also argue to the effect that the Intoxilyzer 5000 has been previously accepted as scientifically reliable in various appellate court cases, and thus the verity of the Intoxilyzer 5000 has already been determined to be established. A review of these cases, however, discloses that the issue herein was not squarely addressed in any of those cases. We find nothing in those cases which provide that the computer source code of the Intoxilyzer 5000 is above challenge. As such, we are unpersuaded by this argument.

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