What is the national minimum drinking age act of 1984 and what happens to those who violate it

The National Minimum Drinking Age Act of 1984 (23 U.S.C. § 158) was passed by the United States Congress on July 17, 1984.[1][2][3] It was a controversial bill that punished every state that allowed persons below 21 years to purchase and publicly possess alcoholic beverages by reducing its annual federal highway apportionment by ten percent. The law was later amended, lowering the penalty to eight percent from fiscal year 2012 and beyond.[4]

Despite its name, this act did not outlaw the consumption of alcoholic beverages by those under 21 years of age, just its purchase. However, Alabama, Indiana, Kansas, Michigan, North Carolina, Pennsylvania, and Vermont, and the District of Columbia extended the law into an outright ban. The minimum purchase and drinking ages is a state law, and most states still permit "underage" consumption of alcohol in some circumstances. In some states, no restriction on private consumption is made, while in others, consumption is only allowed in specific locations, in the presence of consenting and supervising family members as in the states of Colorado, Maryland, Montana, New York, Texas, West Virginia, Washington, Wisconsin, and Wyoming. The act also does not seek to criminalize alcohol consumption during religious occasions; (e.g. communion wines, Kiddush).

The act was expressly upheld as constitutional in 1987 by the United States Supreme Court in South Dakota v. Dole.

The United States is one of only four developed countries in the world that has a nationwide drinking age of over 18, with the other three being South Korea (19), Iceland (20), and Japan (20).