The term "blood alcohol level," sometimes also called "blood alcohol content," is simply a measurement of the amount of alcohol in the blood. Police use breath tests to measure blood alcohol levels and evaluate the intoxication of suspected drunk drivers. Doctors use a blood test to check this level in someone with alcohol poisoning. The physical effects of alcohol intoxication grow as a person's blood alcohol level increases. In general, a blood alcohol level of 20 mg/dL to 50 mg/dL represents mild intoxication, while levels of 300 mg/dL to 400 mg/dL can cause unconsciousness, delirium, and death.