The whole concept of "legalization" is looking at things backwards. It seems to me it is taking things that are "illegal" and then having the government say "we could have killed you for doing this yesterday, but today we'll let you live- as long as you pay all the applicable extortion... um, 'taxes'."
Instead of "legalizing" anything- marijuana, gay marriage, concealed carry, raw milk, whatever- The State needs to keep its perverted hands OFF. The State has no real authority to "legalize" or "criminalize" anything.
No, murder shouldn't even be "illegal", since it has nothing to do with The State. Yes, murder is wrong; the "laws" against it have nothing to do with its wrongness. And even when "legalized"- such as "war" or murder by cop, it is STILL wrong.
Government has stolen more than your money and other property. It has stolen your sovereignty and, in most cases, your ability to act on it without risk of being kidnapped, robbed, and/or murdered. Take it back and stop asking permission.
