The measures that may be taken in the name of self-defense must be clearly sanctioned and defined by law. If you shoot someone who invades your home, you must be prepared to show that the shooting was indeed an act of self-defense and that your behavior was in accordance with the law. The decision about what kind of force can be used, and under what circumstances, cannot be left to the discretion of every individual. Contrary to the libertarians, anarchy represents a massive danger to individual rights. The law must codify the limits of proper self-defense.

But if the justification is the need to subdue, not a criminal, but an oppressive state, what kind of legal codification could there be? Who is going to set the limits? Certainly, there cannot be laws endorsing your arming yourself for the purpose of disavowing the government and its laws. This proposed justification reeks of anarchism. 

If our government does ever descend into dictatorship, we definitely have the moral right to forcibly resist and to overthrow it. Today, though, when we still have relative freedom, we are not entitled to physically battle the government. We have a right to repel a robber’s attempt to use force against us, but we have no right to shoot the tax collector coming to our door, even though he too is initiating force against us. Similarly, a person cannot claim a right to acquire arms, whether handguns or howitzers, on the grounds that he might need them to fight some future despotism—a despotism as defined by him. His actions, in today’s context, pose an objective threat to the innocent.