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.

Comments

Not in Europe

[Ubi_NL]

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.

Re:Why does this need to be computerized?

[hey!]

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.

Re:...which is why

[cayenne8]

You agree to let them be invasive when you accept your driver's license.

Not true, again, it depends on the laws of your state.

It has been awhile since I last reviewed mine, now that I think about it, but from my last look...and after talking to a local lawyer, here are some things if you happen to get pulled over.

First, do NOT take any field sobriety tests, especially the walking the lines, touching the nose, etc....especially if you think you might be close to the limit. All they are doing there, is collecting evidence against you on camera, that's it.

Don't help them out.

Refuse a field breath test.

Same reason as above, you're only helping them collect evidence against you.

If you think you are at all close to legal levels, while being polite, do not talk much. Answer few to no questions about where you were, what you've done and for certain do not tell them you have been drinking.

And face facts, if they DO think you are impaired, nothing you can say or do will keep them from taking you in. If this is your situation, you basically need to just put your hands out for the cuffs and quietly go for a ride, you are doing to do that regardless of any actions you may try, you cannot talk your way out of it, etc.

Again, do NOT help them gather evidence against you.

Last I looked, in my state, if this is your first offense, you can and SHOULD refuse all breath and blood tests. The only time they can force you to take a blood test, is if you were in an accident, and someone was hurt/killed, then you can be compelled.

Otherwise, if this is first offense you can refuse all tests, and you should.

Then, get a good lawyer, and if you've done your job of not helping them gather evidence against you, he/she will likely get you off at the most with a wreckless driving.

Of course, this sucks, but it is better than a DWI.

If a 2nd time happens, and well...you should have learned your lesson the first time....do the same and do not help them gather evidence against you...this time if you refuse the breath test, there are some consequences. They recently passed some new laws and I honestly have not studied them....but to the best of my knowledge, you can at least get a lawyer to talk them into a limited license to get to/from work and such.

Now....should be you driving and drinking in the first place?

Well, in this day in age...no. There is uber...it is cheap, plentiful and they can cart your drunk ass anywhere. These days, it just isn't worth it to risk getting caught.

But I mention it, because, well...shit happens. And with the BAC levels reduced to such stupidly LOW levels (0.08)....you can get very close to the legal limit as a grown man, having only 2-3 glasses of wine with a meal....and they can bust you, yet you may not even be close to impaired.

So, keep that in mind.

Again...this varies from state to state. If you drink, you should know way ahead of time, what the laws in YOUR state are, and if possible, talk to a lawyer to know what to do and not to do.

And really with ANY interaction with the police, the best thing you can do is NOT say anything....your right to keep silent is the best thing going for you, and remember the police, no matter what they say, are NOT there to help you, they are there to try to gather evidence to charge someone (possibly YOU) with a crime.

Be polite, comply...but don't help them out.