Among the approaches suggested for dealing with drinking-driving is for an unimpaired passenger to drive. However, at present little is known about the BACs of passengers. A few studies have examined BACs of injured or killed passengers. We provide passenger BAC data for a representative sample of the nighttime driving population. In those vehicles with two or more passengers and at least one drinker, the passenger had the higher BAC in 68% of cases. However, 61% of legally impaired drivers had no passenger and among legally impaired drivers with a passenger, 53% of passengers also had an illegal BAC.

Virtually all research on drinking-driving to date has focused, understandably, on drivers. However, in order to know whether programs designed to move drinkers out of the driver's seat and into other positions in vehicles or into other modes of transportation altogether, information is needed about passengers in automobiles and taxicabs, as well as mass transit passengers, and among pedestrians.

Waller (1972) reported on alcohol consumption by fatally injured passengers as well as drivers in a small California study conducted in the early 1960s. He found that only about one in four passengers of impaired drivers would be been a suitable alternate driver. However, this study was conducted long before the idea of using a designated driver was promoted.

In a study of over 20,000 casualty traffic crashes in British Columbia, Mercer (1984) found that passengers in the same vehicle as a drinking driver were the most likely victim (besides the drinking driver). Passengers with drinking drivers accounted for 55% of persons injured or killed by a drinking driver;​ passengers of sober drivers accounted for only 35% of their victims.