South Dakota v. Dole (1987) - legal drinking age. State some factsabout this law

In that case, the state of South Dakota did not agree to the federal congressional law that only people of 21 and older are allowed to drink as they allowed 19 year-olds and older to purchase beer if it's up until the 3.2% of alcohol limit in it. The supreme court declared that the law of 21 is constitutional and that South Dakota can't object and have it's own laws, and declared that if the state does not conform to the laws, they would lose federal funding.