The American Medical Association and federal entities recommended states with driving laws under the influence to set blood alcohol concentration levels at 0.15 percent or less but were free to establish their guidelines. Also, the states had different minimum ages to consume alcohol, ranging between 18 and 21 years, but according to research, the higher the minimum age to drink alcohol, the lower was the rate of driving offenses while intoxicated.
This changed in 2000 when Congress passed a law that required each state to set its blood alcohol concentration limit at 0.08 percent and establish the minimum age to consume alcohol in 21 years. Since the sanction for breaking the law consisted of the loss of millions of dollars in federal highway funds, all states complied with it promptly. In 2013, the National Transportation Safety Board of the United States suggested lowering the blood alcohol concentration limit to 0.05 percent.