These devices are installed inside a vehicle and require the operator to pass a breath-alcohol test to determine impairment. If the driver's breath-alcohol content is measured above a certain threshold (usually 0.04 percent, or half the legal limit), the ignition locks and the vehicle will not start.
However, the positive effects of these systems are limited to how long they are actually in place. Because they are imposed as a penalty for DUI conviction, they are almost always temporary. But researchers with the University of Michigan Health System wanted to know what would happen if the devices came standard in all new model vehicles - permanently, and not just for those drivers who were being punished.
The results, published in the American Journal of Public Health, are astonishing. Over the course of 15 years, we could potentially reduce the number of drunk driving fatalities and injuries by 80 percent. In real terms, that would be 59,000 lives saved. It would be 1.25 million people spared serious injuries. It would mean $340 billion saved in injury-related costs associated with drunk driving accidents.