In-transit breath tests required for devices known as ignition interlocks have been implicated in dozens of crashes, an investigation by The New York Times claims. Nearly 350,000 people in the United States have interlocks, and 34 states require people with DUI offenses to install the devices, which require a breath test to allow a car to start and “rolling retests” while the journey progresses. Retests require the driver to pick up the device and blow into its mouthpiece for several seconds, or else the car’s headlights flash and its horn honks until the driver turns off the engine. In one accident reported by the Times, a driver blacked out from blowing on the device and crashed into a tree, nearly severing his left hand. In California, a man attempting a rolling retest on a busy highway crossed the road’s dividing line and hit another car, badly injuring a woman and killing her husband. However ,the prevalence of the devices is set to grow, and one study found that states mandating them for all drunken-driving offenders had 15 percent fewer fatalities from alcohol-related car accidents.