All people have certain rights, these rights are the ones that you are born with. Governments were created as a means or a tool to safeguard the rights of humans. Governments derive their authority through the permission of the people that they would attempt to govern. A government's authority to protect itself is merely the collective right to self defense. A government cannot govern a people who do not wish to be governed, it would be impossible to do so.
Governments can be distorted and corrupted to deprive one segment of the people their rights to the benefit of others. When this happens, it is the responsibility of the people to alter or abolish a government that acts in such a manner. That does not always mean force. It can mean the ballot box, or even redressing one's grievance in court or through the press.
The right to self defense is fundamental. The right to defend yourself from a single attacker, a dozen attackers, or even a million attackers is a human right. The right to do so, like all other rights, is not absolute. If you rape, you do not have the right to defend yourself from her counter attack. You may have the ability, but not the right. One person's right can never be used to rightfully deprive another of their rights.
The same with a government- just because a government has the ability and the power to carry out an act does not mean that they have the AUTHORITY to do so. Of course, if no one takes a stand and refuses to allow such a trespass, the abuse will continue. "All that is necessary for evil to prevail is that good men do nothing."
The right to protect yourself implies a right to the tools to do so. Firearms are currently the most efficient tools of defense.
The COTUS merely exists to prevent the majority from enslaving the minority- the old axiom that "popular speech need not be protected" is still true. Once we have outlawed individual rights, we have lost our moral authority. History will judge just how effective the COTUS was in that pursuit.