Isn’t that like forcing people to buy health insurance? I’m not trying to be flippant. What’s the difference?
Sounds like the SD politicians are having some fun poking the Obama bots...
To your question : State governments, unlike the federal government, are not limited to the US Constitution on federal enumerated powers ?
Also there is the Federal Militia Act of 1792, male citizens were required to equip themselves with firearm and military gear:
http://www.freerepublic.com/focus/f-news/2666765/posts?page=24#24