Orange County, California, over 1,000 drivers were diverted to a parking lot late one night. They were asked to fill out a questionnaire about their evening, then interrogated by graduate students trained in intoxication detection. How did the driver talk? Walk? Was there alcohol on their breath? Were there bottles or beer cans in their car? After the interviewers made their diagnoses, the drivers were given a blood-alcohol test. Here’s how many drunk drivers were correctly identified by the interviewers: 20 percent.
