What government interest is served by denying 2nd Amendment rights to 18-20 year olds?
Good point. The age restriction of 21 years or older is one of the last vestiges of the statutory requirement of 21 to vote or be legally considered an adult. In the military, 18-yr olds and even 17-yr olds are routinely issued handguns and expected to use them.
True, teenage drivers are responsible for a hugely disproportionate number of traffic accidents, and the drinking age was raised to 21 after the number of accidents spiked when it was lowered to 18. But, neither driving nor drinking are Constitutional rights. The case is a slam-dunk.
Violence is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and valorous feeling which believes that nothing is worth violence is much worse. Those who have nothing for which they are willing to fight; nothing they care about more than their own personal safety; are miserable creatures who have no chance of being free, unless made and kept so by the exertions of those better than themselves. Gary L. Griffiths, Chief Instructor, Advanced Force Tactics, Inc. (Paraphrasing John Stuart Mill)