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Researchers Say a Breathalyzer Has Flaws, Casting Doubt On Countless Convictions (zdnet.com)
An anonymous reader writes: The source code behind a police breathalyzer widely used in multiple states -- and millions of drunk driving arrests -- is under fire. It's the latest case of technology and the real world colliding -- one that revolves around source code, calibration of equipment, two researchers and legal maneuvering, state law enforcement agencies, and Draeger, the breathalyzer's manufacturer. This most recent skirmish began a decade ago when Washington state police sought to replace its aging fleet of breathalyzers. When the Washington police opened solicitations, the only bidder, Draeger, a German medical technology maker, won the contract to sell its flagship device, the Alcotest 9510, across the state. But defense attorneys have long believed the breathalyzer is faulty. Jason Lantz, a Washington-based defense lawyer, enlisted a software engineer and a security researcher to examine its source code. The two experts wrote in a preliminary report that they found flaws capable of producing incorrect breath test results. The defense hailed the results as a breakthrough, believing the findings could cast doubt on countless drunk-driving prosecutions.
In .nl at least, these breathalyzers are used by police to do a quick test only. If the result is positive, the suspect is carted to a police station where a much more accurate machine is used to determine the blood alcohol levels. Only that ladt number is used as evidence.
I was assuming all countries had similar methods.
If an experiment works, something has gone wrong.
A Drunk Driving conviction is big business in California.
Of course they would tweak the test to get more and more money.
You can easily spend $15K if you get one.
FYI, if there's even a SHRED of doubt, always opt for the blood test. Especially considering things like mouth wash, or ketones can result in a false positive. As an added bonus, that extra time waiting for the blood draw means your BAC is decreasing.
Thanks MADD, you co-opted the 5th amendment with your prohibition agenda.
The neurological deficits of drinking (and using many other drugs) persist long after blood levels have dropped to zero. So either develop tests that measure actual impairment (and bust a lot more people) or just admit that so many people are impaired but sliding under the limits that we may as well just let them drive.
Have gnu, will travel.
So in most cases they use the breathalyzer along with a field sobriety test to determine if they should arrest a driver, after which they normally draw a blood sample for a more precise test. (In most states, drivers can refuse the tests and receive an automatic license suspension, though that's often not as bad as a conviction, but it doesn't preclude a conviction based on the sobriety test alone.)
So we have lots of cases where there is both breathalyzer test data and blood test data. This gives a huge amount of data that can be correlated. Also, the times of the test should be recorded, so expected declines due to delays between the two tests can be computed. So all we need to do is gather up the data from a few years of use, and then we can see what the reliability of the breathalyzer is in comparison to the blood test.
We know that any test can fail (equipment failure, cross contamination, operator error, etc.), but this will give solid data on the expected error.
The issue isn't with the software per se, but what the examination of the software revealed about the units as a system. If you used op amps instead of microcontrollers most of those issues would still be there.
The sensors used are temperature sensitive. The configuration used by the police disabled ambient temperature checks, which I guess you could call a digital issue. The device lacks a breath temperature sensor, which means that people with warmer than average breath could get false positives.
These devices also should be re-calibrated after a fixed number of uses; instead the state was re-calibrating them on a fixed schedule. While that schedule might work for an *average* device, devices that had been heavily could b e giving spurious readings.
On the flip side the device uses two different types of sensors to measure alcohol, and rejects readings where the sensors give different answers. This might mitigate some of the defects in how the state used them, but nobody can be sure. All we have is the assurance of the state authorities that the devices "have been tested to meet our business needs," without any specifics about what the test entailed.
The danger of these things is that they give you a number and it all seems so scientific and precise. You don't get the hemming and hawing that comes with a human opinion, metadata that helps you decide how certain you should be of that opinion. Layman don't understand the limitations of technology, they assume the tech should "just work". I'd trust a sophomore engineering student to devise policy for using these things over a police chief with decades of law enforcement experience.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Thanks MADD, you co-opted the 5th amendment with your prohibition agenda.
You have no idea how true this is. In New Jersey, when they arrest you, they read this laminated card with a a detailed description of how and why you have no rights, why you must submit to a breathalyzer on the spot or automatically be found guilty as well as face additional (double) penalties for refusing, and how you have no right to consult with a lawyer before deciding. You are also not allowed to ask any questions or clarifications. If you have any questions, they simply repeat the card verbatim.
In addition to the completely obvious unconstitutionality of it, they see no hypocrisy in how the state's official position is that you "consented" to the test, even though if the test does come up positive, that proves that your consent was given while you are drunk, which in any other part of the legal system means that you did not consent.
Then of course there is the issue of how haphazardly calibrated these machines are, how wildly inaccurate they are, and so on.
Even still, even when the prosecution can't prove probable cause, and even if they lose the evidences for 9 months while they jerk you around, with constant continuances, they still end up convicting 100% of the time. No jury BTW, just a judge who is buddies with all the cops.
Meanwhile, if you are rich, you can just bypass it all as your expensive lawyer winks at the judge and you don't even lose your license.
Our "justice" system is a complete joke.
You don't have to be driving drunk to be pulled over and accused of it.
Why did you call him an asshole? He didn't say anything about driving drunk, and it's obviously assumed that everyone is talking about a situation where the driver is sober. But what do you do when a cop wants to test the sobriety? Don't we want to have DWI/DUI laws? If you have these laws, you need some way to investigate suspects. But impaling innocent people (yes, I'm using totally loaded language here, on purpose) is something most of us don't want.
So a whole game develops in the middle ground of uncertainty. Go too far one way, and you don't really have effective laws against drunk driving. Go too far the other way, and you're poking holes in innocent people to make them bleed. Breathalysers were a great compromise .. if only they hadn't tried to keep the inner workings a secret from the very society that judges the accused, thereby making them bullshit "evidence." FAIL.
Open up the breathalysers to auditing and maintenance and you'll have a useful technology. Just like we eventually determine with everything else that's important (e.g. the software in your desktop computer). Anything you can't audit, is bullshit.
It shouldn't be the lowest common denominator, that opens up WAY too broad of a dragnet.
If it were 1 in 100 that 0.8 was too high to drive; I would agree with you. If it is 1 in 4 then, absolutely, even if 3 can drive safely at that limit- 25% not being able to is a significant number. 0.8 is actually higher than a lot of states in the Union, and higher than a lot of Asian and European countries.
I have a simple rule. If I have drunk any alcohol; I don't drive. Even though after a couple of beers or a couple glasses of wine, I don't feel impaired, I don't drive if I've drunk anything. It's really not worth it. It's not worth being impaired even if I feel fine; it's not worth getting arrested if my blood alcohol is higher than I think.
It's not like it's that inconvenient to skip a drink every once in a while if you have to drive.
"That's the way to do it" - Punch