While ignition interlock devices have prevented numerous drunk driving crashes, an investigation by the New York Times finds that the gadgets have also caused many accidents.

The newspaper’s investigation found that interlocks have been effective as one study concluded states mandating their use have seen 15% fewer fatalities from alcohol-related crashes.

What is an ignition interlock?

The device is installed under a vehicle’s dashboard or console and is connected to a long tube that the driver blows into and hums for a certain amount of time. If no alcohol is detected, the car will start.

Minnesota DWI offenders who test at a 0.16% blood alcohol concentration (BAC) are required to install the device on their vehicles along with anyone with a prior DWI conviction in the past 10 years.

How many Minnesota drivers use ignition interlocks?

The most recent statistics from the Traffic Injury Research Foundation reports 8,093 interlocks were installed in Minnesota in 2017 with the annual cost for the devices at around $1,000.

In all, 12,779 vehicles used an ignition interlock device in 2017, an increase of nearly 10% from 2016, according to companies that manufacture the machines.

Rolling retests lead to distracted driving

Once drivers successfully pass the initial breath test and start their vehicle, they are not done being tested. They are prompted at random intervals while the car is moving to retest by blowing into the tube again to make it harder for drivers to cheat the system.

However, the Times found dozens of fatal and other severe crashes as a result of these rolling retests, where the driver’s attention was taken off the road to focus on the interlock. If a driver fails a test while moving, the car’s headlights flash and the horn honks until the driver turns off the engine.

No safety standards exist for ignition interlocks

While the National Highway Traffic Safety Administration’s (NHTSA) initial guidelines required drivers to stop their vehicles before performing retests, that provision was abandoned after manufacturers objected, saying rolling retests are safe while arguing it is impractical for drivers to pull over.

Interlock devices often show false positives

Ignition interlocks can put drivers in jeopardy even when they are safely used. The issue is over the accuracy of the devices themselves. The Times found that even the most reliable breath-testing machines experience software glitches, human error and maintenance problems.

Courts across the United States, including Minnesota, have tossed out more than 50,000 tests found to be flawed. Ignition interlocks contain even cheaper and less reliable technology than most standard breath-testing devices used in police stations across the country.