Researchers Find Breathalyzers To Be Just More Faulty Cop Tech Capable Of Putting Innocent People In Jail

from the may-as-well-just-go-back-to-hunches dept

Good news for motorists: law enforcement is using something just as unreliable as $2 field drug tests to justify arrests and searches. Field drug tests have been known to declare donut crumbs meth and drywall dust cocaine. Yet they're still in use, thanks to their low price point. A costlier apparatus, used to determine blood alcohol levels during sobriety tests, appears to be just as broken as cheap drug tests.

Alcotest, made by German medical tech company Draeger, is used by a large number of US law enforcement agencies. Challenges to test results led to Draeger turning code over to defense attorneys, who soon discovered a lot of variables affected breath tests -- many of which weren't addressed by the device's software or default settings used by officers. Zack Whittaker at ZDNet has the full report:

One attorney, who read the report, said they believed the report showed the breathalyzer "tipped the scales" in favor of prosecutors, and against drivers. One section in the report raised issue with a lack of adjustment of a person's breath temperature. Breath temperature can fluctuate throughout the day, but, according to the report, can also wildly change the results of an alcohol breath test. Without correction, a single digit over a normal breath temperature of 34 degrees centigrade can inflate the results by six percent -- enough to push a person over the limit. The quadratic formula set by the Washington State Patrol should correct the breath temperature to prevent false results. The quadratic formula corrects warmer breath downward, said the report, but the code doesn't explain how the corrections are made. The corrections "may be insufficient" if the formula is faulty, the report added.

The Washington State Patrol, whose device/software was being examined in this case, said it did not install the breath temp component. That eliminates one questionable variable in this case. Other law enforcement agencies may have installed the component without realizing it could result in false positives. But it's far from the only variable affecting test results the examination of Draeger's software uncovered. The Washington State Patrol also disabled another feature that might have prevented false positives.

The code is also meant to check to ensure the device is operating within a certain temperature range set by Draeger, because the device can produce incorrect results if it's too hot or too cold. But the report said a check meant to measure the ambient temperature was disabled in the state configuration. "The unit could record a result even when outside of its operational requirements," said the report. If the breathalyzer was too warm, the printed-out results would give no indication the test might be invalid, the report said.

The State Patrol was more equivocal in its repudiation of this finding. It said it had been "tested and validated in various ambient temperatures." Draeger itself insisted the unit will not produce readings if the device is operating outside of recommended temperature ranges.

The report also noted there appeared to no steps taken to counteract normal wear-and-tear. The fuel cell used to measure alcohol levels decays over time -- a time period accelerated by frequent use (sobriety checkpoints, for instance). This can also affect test results if the decay isn't factored in. Draeger says its devices should be re-calibrated every year. The Washington State Patrol only require one recalibration six months into the device's lifespan.

Challenges against the device's test results have occurred in other states. Massachusetts -- a state where substance abuse-related evidence has never been more unreliable -- hosted one legal battle over the devices' reliability. A ruling in 2014 declared test results obtained over the previous two years "presumptively unreliable" after it was discovered that only two of the state's 392 breathalyzers had ever been properly calibrated.

This battle between critics of the devices and their deployment methods (untested, uncalibrated) and a judicial system that still insists the devices are reliable enough has gone on for most of a decade. Added to the mix is Draeger's own legal action. This preliminary report, distributed to defense lawyers at conference last year, was the subject of a cease-and-desist letter from Draeger, which claimed the report violated a protective order it had obtained from a US court, prohibiting the distribution of its source code. But no source code was distributed and the C&D appears to Draeger attempting to prevent questions about its device's reliability from spreading further than a handful of court cases. And in those legal challenges, Draeger has been able to keep discussion of its devices and software under wraps via injunctions.

While the report's authors claim the report is still in its preliminary stages and should not be considered the final word on breathalyzer reliability, this initial examination doesn't suggest deeper digging will find a more reliable machine underneath the surface-layer flaws.

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Filed Under: alcotest, breathalyzers, drunk driving, false positives, police, source code

Companies: draeger