Charles Short, Guilt by Machine: The Problem of Source Code Discovery in Florida DUI Prosecutions

61 Fla. L. Rev. 177 (2009) | | | |

ABSTRACT :: Breath testing results stand at the core of most driving under the influence (DUI) prosecutions. Florida law provides that an individual is guilty of driving under the influence when he drives, or is in actual physical control of a vehicle, while under the influence of alcohol or a controlled substance, such that his normal faculties are impaired. To obtain a conviction, the state must prove the element of impairment beyond a reasonable doubt. A breath alcohol level of 0.08 grams of alcohol per 210 liters of breath satisfies the element of impairment. It comes as no surprise, then, that many DUI cases hinge on these results.

Breath testing machines, however, often malfunction, leading to incorrectly high blood alcohol readings, sample volume irregularities, and unexplained readings. False positives can result from diabetes, exposure to paint thinners, and even being on the Atkins Diet. Glitches have afflicted the Intoxilyzer 5000 and the Intoxilyzer 8000, the two breath testing machines currently used in Florida. Given the centrality of breath test results to many DUI prosecutions, these malfunctions provide concern. Further concern arises from the fact that the reliability and accuracy of these machines cannot be independently verified. Florida courts and the Florida Legislature have foreclosed all attempts by defense counsel to obtain discovery of technical information about the breath testing machines. As a result of their highly deferential treatment from the state, the Intoxilyzer models have become “mystical machine[s].” The manufacturer has assured the State of Florida that the Intoxilyzers work, and law enforcement has determined, to its satisfaction, that the machines produce accurate results. However, defense counsel is unable to independently verify any of these propositions. Thus, the outcome is truly circular: the machine is reliable because it produces results; the results are right because the machine is reliable.

This Note explores the issue of source code discovery by DUI defendants. Part II of this Note examines the case law and statutes used to shield breath testing machines from scrutiny. It examines both the approach taken by Florida and the approaches adopted in other states. Part II also discusses the application of trade secrets protection to the source code of breath testing machines. Part III further examines the problem of source code discovery through the lens of the Confrontation Clause of the Sixth Amendment to the United States Constitution. Finally, Part IV concludes by posing a solution to the problem that more properly balances the important rights of the accused with the trade secrets concerns of the breath testing machine’s manufacturer. Florida should allow a DUI defendant to review the computer source code of a breath test machine if impairment is at issue in the case. Barring that, the state should negotiate for source code access to allow defendants to verify the machine’s accuracy.

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