We don’t need to justify why we should be allowed to do something…

Exactly.

I once was sitting with my co-workers and eating lunch, when one co-worker remarked that guns cause so many problems that she didn’t understand why they were allowed. Um, maybe because it violates people’s fundamental rights for them not to be allowed?

Enough with the argument that, “No one needs an AR-15.” So? I don’t need to need something in order to be allowed to do it. If you think that AR-15s (or anything, for that matter) should be banned, it is your responsibility to prove that they need to be banned. The burden of proof must always be placed on those who wish to control the actions of others, as opposed to those who wish merely to be left alone to live in a way that suits their preferences.

People have the right to do anything that they want, as long as it does not violate the rights of anyone else. If you are arguing that I should not be allowed to do something, I do not have to justify why I should be allowed to do it; you have to justify why I should be prohibited.