Why Is the Legal Drinking Age 21?

Posted On August 27, 2018 Criminal Defense,Drunk Driving Charges

The minimum legal drinking age in the U.S. for all states, including Arizona, is 21. Those who drink under this age limit may face charges such as a minor in possession (MIP), or other civil and criminal penalties. Most people, though, are unaware of the reasoning or research associated with the establishment of this age requirement. It may seem arbitrary, but public health and safety experts have valid reasons for suggesting this age restriction.

Enhancing Public Health and Safety

The Centers for Disease Control and Prevention (CDC) is one of the largest public health agencies in the United States, and also one of the main collectors of data regarding drinking age and its impact on society at large. Over the course of many decades, the CDC found that enforcing the age 21 limit improves the overall health of society. According to their research:

  • States that observe a legal drinking age of 21 experience a 16% median decrease in motor vehicle accidents.
  • States that adopted the age 21 drinking limit saw less drinking among younger populations. The reported previous month drinking in adults aged 18 to 20 dropped from 59% in 1985, when the age limit took effect, to 40% in 1991.
  • The CDC reports that changing the age limit to age 21 also seems to have had an effect on other outcomes, such as a decrease in birth defects, decreases in suicides and homicides, and dependence on other drugs.

Drinking in Those Under the Age of 21 Continues To Be a Problem

Examining the statistics pertaining to alcohol use among young people will show that drinking poses a threat not only to others but also to the young drinkers themselves. Excessive drinking directly contributes to the death of more than 4,300 young adults under the age of 21 each year, according to the CDC.


  • Underage drinking leads to an estimated $24 billion in costs to the U.S. economy.
  • Injuries and illnesses related to underage drinking lead to an average of 189,000 annual ER visits.
  • More than 90% of all alcohol consumed by underage drinkers is defined as binge drinking (more than five drinks in one occasion for boys, or four drinks in one occasion for girls).
  • Drinking under the age of 21 is also associated with death from alcohol poisoning, which causes chemical changes in the brain that impact development and decreased performance in school.

But Why 21?

Research shows us that alcohol consumption can be dangerous for young people. But why enact the age limit at 21? Is it arbitrary? Actually, the law is very intentional.

The logic of the age 21 limit dates back to English common law. Among many other things, 21 was the age at which a person could vote or become a knight, officially making the transition into adulthood. More modern reasons exist for this age limit. The teenage brain is still making critical developmental changes that can affect cognition and other mechanisms for the rest of a person’s lifetime. By the age of 21, much of this critical brain development is complete. Twenty-one-year-olds are far more capable of making rational decisions and treating alcohol responsibly than someone younger.

The National Minimum Drinking Age Act of 1984 required states to comply with the new age 21 limit or lose up to 10% of their federal highway funding, which leads to the majority of states falling into line fairly quickly.

Though the drinking age might not seem fair to younger populations, important reasons for it exist. These reasons pertain not only to the health of younger people in general but the safety of society as a whole.