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The first jurisdiction in the United States of America to adopt laws against drunk driving was New York in 1910, with California and others following. Early laws simply prohibited driving while intoxicated, with no specific definition of what level of inebriation qualified. The first generally-accepted legal limit for blood alcohol concentration (BAC) was 0.15 (in 1938, the American Medical Association created a "Committee to Study Problems of Motor Vehicle Accidents"; at the same time, the National Safety Council set up a "Committee on Tests for Intoxication". After some study, these two groups came up with their findings: a driver with 0.15 BAC or higher could be presumed to be intoxicated; those under 0.15 could not).
In the US, most of the laws and penalties were greatly enhanced starting in the late 1970s, and through the 1990s, largely due to pressure from groups like Mothers Against Drunk Driving (MADD) and Students Against Driving Drunk (SADD) and leaders like Candy Lightner. Most significantly:
1. The legal presumption of intoxication from blood alcohol concentration was reduced to 0.10; more recently, and with federal pressure, all states have further reduced the limit to 0.08%.
2. A second drunk driving offense was created and eventually adopted in all states: driving with a BAC of 0.08% or higher; this was typically charged in addition to the traditional offense of driving under the influence.
3. Zero tolerance laws were enacted which criminalized driving a vehicle with 0.01 or 0.02 BAC for drivers under 21.
4. Automatic license suspension laws were universally adopted which provided for the immediate confiscation and administrative suspension of the driver's license if the BAC was 0.08% or if the driver refused testing.
MADD and other organizations are also widely cited for getting the drinking age raised to 21 in those states where it had once been lower. Also during this era, enforcement of drunk driving laws became a priority for police for the first time, and constitutional impediments to such practices as sobriety checkpoints were removed.