Alcohol breath tests, a linchpin of the criminal justice system, are often unreliable, a New York Times investigation found.

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, 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


A fateful trip

The drunkometer

Starting to panic

Secret software

"Throw caution to the wind"

Insomnia and shame

Disregarding truth and accuracy

Homebrewed chemicals

"Serious errors of judgment"

42,000 convictions at risk