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Flaws in Alcotest 9510’s source code could affect DWI convictions

| May 24, 2018 | DUI/DWI |

A breathalyzer is a breathalyzer, right? You might be under the impression that all breath testing machines are the same, but they’re not. Each one is manufactured for profit by a private company. Intoxilyzer, Breathalyzer, Alcotest, Intoximeter — each brand must meet certain standards set by the National Highway Traffic Safety Administration, but the exact details of how they operate are considered the intellectual property of the producer.

That does not mean that their accuracy cannot be questioned or challenged in court. Criminal defendants have a constitutional right to fully challenge any evidence brought against them. When the defense suspects a type of breathalyzer is inaccurate, it can ask the court to allow it to examine the secret, proprietary aspects of the machine. This often involves hiring an expert in software engineering to look at the source code.

That is precisely what happened in a recent drunk driving case in Washington State. The case involved the Alcotest 9510, a breath testing machine manufactured by Draeger which is used in numerous states. Two software engineering consultants were brought in to review the machine’s source code because the defense suspected the machine may produce inaccurate test results under some circumstances.

This was not the first time the Alcotest 9510 has drawn the scrutiny of defense attorneys and courts. Attorneys in both New Jersey and Massachusetts have challenged the accuracy of the machine, albeit unsuccessfully. The accuracy of individual tests, however, was challenged successfully in Massachusetts last year, when it was discovered that all but two of the state’s Alcotest machines had not been properly calibrated. A judge found those test results “presumptively unreliable” and thousands of cases may yet be thrown out.

In a nine-page report, the consultants said they were skeptical the Alcotest 9510 can be relied upon to produce accurate test results under all circumstances.

The consultants found a number of technical problems with the machine. Without getting into too much detail, it seems that the machine may produce inflated results when breath or ambient temperature are above the expected level. Also, a certain sensor is based upon a fuel cell which produces increasingly inflated results as it degrades over time. The software attempts to compensate for these issues but the consultants said those attempts may be insufficient.

The Washington court has not yet ruled on the issue, but we should all be concerned. Some of the test results were inflated enough to cause an innocent person to appear guilty.

If you have been arrested for drunk driving, be sure to work with a defense attorney who knows how to challenge the results of breath tests. They may not be as accurate as they seem.

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