A law is only as good as the ability to enforce it. Drunk driving is major cause of disability and premature mortality in the U.S., with the Centers for Disease Control and Prevention estimating that alcohol-impaired driving is responsible for about 10,000 deaths annually. For this reason, driving with a blood alcohol concentration of 0.08 or higher is illegal throughout the country, with laws and penalties varying from state to state. All states, for example, have laws requiring judges to mandate that some or all convicted drunk drivers install in their vehicles ignition interlocks, which analyze a driver's breath and disables the engine if alcohol is detected. Pennsylvania mandates them for repeat convictions; New Jersey does the same, and adds drivers with high blood alcohol content (0.15 and above).
These laws would be of little value, however—and ignition interlocks wouldn’t exist— if there wasn’t an efficient and effective way to measure drunkenness. Enter a brief history of the Breathalyzer—a tool of public health.
While the observation that people carry alcohol on their breath is probably as old as booze itself, the scientific study of how to detect intoxication in the U.S. appears to have developed out of necessity: how to enforce prohibition laws during the roaring 20s, when moonshine flowed and fast cars were cheap.
A 1927 paper by Emil Bogen, "The diagnosis of drunkenness—A quantitative study of acute alcoholic intoxication,” for example, described the emergent problem of drunk driving and proposed that physicians could use science to develop enforcement strategies. That same year, a brief piece in Popular Science (note the image, the dapper gentleman is looking suspiciously sloshed) described an invention by chemist W.D. McNally that purportedly could detect drunkenness using chemicals that would change color when the suspect breathed into a tube that passed air through them. As the article notes about the device’s utility, “police might test auto drivers suspected of drunken driving” or “doubtful wives might test their errant husbands before admitting them late in the evening.”