The National Minimum Drinking Age Act, signed supposedly to lower drunk driving deaths, discourages active debate about the minimum legal drinking age. The Act flies in the face of both the Tenth and the Fourteenth Amendments to the Constitution, stripping from the states the constitutional right to decide what is best for their own people. Along with the Federal Highway Aid Act that decreases highway funding to non-compliant states, it essentially forces states to deny to their adult citizens ages 18 to 20 equal protection under their laws as well as the liberty for adult citizens to decide what (otherwise-legal) substances to put in their bodies.
A better response to reduce highway drunk driving deaths would be to have stricter rules on blood alcohol content for citizens age 18 to 20.