Police Use Junk Science To Secure Convictions.
The NYT is doing it’s job and trying to expose the flaws in the technology of alcohol breath test machines.
A million Americans a year are arrested for drunken driving, and most stops begin the same way: flashing blue lights in the rearview mirror, then a battery of tests that might include standing on one foot or reciting the alphabet.
What matters most, though, happens next. By the side of the road or at the police station, the drivers blow into a miniature science lab that estimates the concentration of alcohol in their blood. If the level is 0.08 or higher, they are all but certain to be convicted of a crime.
But those tests — a bedrock of the criminal justice system — are often unreliable, a New York Times investigation found. The devices, found in virtually every police station in America, generate skewed results with alarming frequency, even though they are marketed as precise to the third decimal place.
Judges in Massachusetts and New Jersey have thrown out more than 30,000 breath tests in the past 12 months alone, largely because of human errors and lax governmental oversight. Across the country, thousands of other tests also have been invalidated in recent years.The machines are sensitive scientific instruments, and in many cases they haven’t been properly calibrated, yielding results that were at times 40 percent too high.
A breath test claims to be able to determine how much alcohol is in your blood just from your exhalations. It sounds legit, right? Alcohol is in the blood, the blood exchanges gases in the lungs, and some of the alcohol in your blood should pass out of the blood and into the air in your lungs as gases exchange. But even so, a couple of breaths isn’t a lot of data to work from. When medical researchers are studying how much oxygen and carbon dioxide and other metabolites are in the air a person exhales, they use a full face mask and have a person breathing through it for a while. They collect a lot of data.
But the police? They use a briefcase sized machine, or a handheld one, to run the test, and in a lot of places, that is the extent of the physical evidence they gather to convict you with. Remember Theranos, that claimed to be able to do blood analysis with a pin prick of blood?
Some places are smart, and they use the machine to basically establish probable cause for a blood test , and then get a blood draw; but a lot of places never bother with the blood test, and the machines? The machines are, ideally, sensitive scientific instruments. Machines that are often left out in the open, where who knows what kinds of abuse they are subjected to. Machines whose guts are protected by secrecy and tight IP, so no one can challenge the veracity of the machines (a classic black box). And we are trusting the police to properly maintain and calibrate these machines.
I’ve said before that we should do away with drunk driving laws. Not because I think people should be allowed to drive impaired1, nor do I think that we should not have additional penalties for drivers who operate impaired, but that the police should focus on the behavior of a driver, and not the results of a black box test that encourages them to.
Relatedly, a family that was the result of similar lazy policing gets a court victory. Again, a case of police using a black box (in this case, a field chemical test) to be the sole driver of an investigation, rather than the first step. And this case is a great example of why we shouldn’t trust the use of police breath tests as the sole bit of evidence for anything other than a warrant. Because the police can not be bothered to understand the tool they are using.