A student asked me over lunch: Some stores have announced that they won’t sell rifles and shotguns to under-21-year-olds. Is that legal, given that federal law only limits sales of handguns to under-21-year-olds, and doesn’t ban sales of long guns to 18-to-20-year-olds?

[1.] Stores’ own age limits don’t violate the Second Amendment, because the Second Amendment limits only the government, not private companies. Likewise for the Equal Protection Clause (plus the Equal Protection Clause generally doesn’t forbid even governmental age classifications).

[2.] The federal Civil Rights Act doesn’t cover retail stores, and doesn’t cover age, so it doesn’t bar such policies, either.

[3.] But about a third of all states ban discrimination based on age in places of…