Okay, so purely on the subject of the District of Colombia's ban (and ignoring my pinko commie views on the subject) :
The District of Colombia is an urban area. It's Washington DC, basically. I don't know how many of you carry pistols around with you (concealed or otherwise) out in the streets...(I bet that thought makes the Secret Service people near the white house happy!)
More to the point, someone who actually knows about guns (Blind_Io) suggests
here that it's better to have a shotgun for home defence than a pistol. Indeed, a representative of the District gives much the same argument - that homeowners can still have a shotgun or rifle to defend their homes with. And very few people are going to walk around the streets with a shotgun or a rifle.
As for the actual Constitution, here's the exact wording again :
Constitution of the USA said:
A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
Many people read it as meaning that the people have the right to guns (or if you suffer from Spoonerisms, you've got the right to arm bears).
I would probably read it as saying the militia have the right to guns - then you have to define what the militia encompasses. Some people will argue that that is meant to mean 'citizen armies' such as the Army Reserves or National Guard, others will take it to mean 'everyone, in the time of emergencies'.
I guess in this regard the phrasing is a little bit ambiguous. It's a bit like how almost any political group can find a Bible quote to match their opinion - even if the original Bible quote means nothing of the sort. I'm thinking of how Jehovah's Witnesses won't take blood transfusions.
So, in summary, I don't know. However I'd welcome the Supreme Court deciding one way another, in clear English, what the Constitution means. And I think that walking around in the middle of a city, with a pistol, shotgun, or rifle, is a bit daft.