The gist: Alcohol breath tests, a linchpin of the criminal justice system, are often unreliable, a New York Times investigation found. Read article here

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 walking a straight line or standing on one foot. What matters most, though, happens next. At the police station, drivers are instructed 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 the U.S., generate skewed results with alarming frequency, even though they are marketed as precise to the third decimal place.

Courts across the country have tossed out more than 50,000 tests in recent years because of problems with specific machines, errors made by police officers and mistakes by labs that set up and maintain the devices. Secrecy makes it hard to find and fix mistakes. The makers of breath test machines consider their technology to be a trade secret and they fight efforts by defense lawyers and independent experts to get a look inside the device. State labs and police departments around the country that manage breath test programs operate with little oversight. That means that even systemic problems rarely come to light.

Large-scale mistakes have sweeping consequences. Massachusetts recently had to toss out every breath test for eight years. More than 28,000 people were convicted based on flawed tests, and other drivers who were likely guilty were let off because their tests were inadmissible. In New Jersey, more than 13,000 drivers convicted with flawed tests can seek to have their cases retried.

In Louisiana, the OWI breath testing program is run by the Applied Science Division of the Louisiana State Police, essentially an arm of law enforcement. They have gone to great lengths to water down the requirements for certifying breath test machines, for calibrating and checking the calibration of the machines, and for overseeing the breath testing programs of the individual police departments. Only a single breath test is required. Anyone who has ever been to the doctor, or has a passing familiarity with science, can tell you that one solitary test result is not good science.

In the immortal words of Frank Baum – “Pay no attention to that man behind the curtain!”