I came upon the political science topic of State Monopoly on Violence and was ruminating on past and contemporary political structures, curious what a system where no party was afforded this monopoly would look like.
At first thought I instinctively felt that the US Federal Government held this monopoly on behalf of the American People. However, as I thought about it more I became curious whether this is actually the case under the Constitution.
In this answer on a decomposition of the 2nd Amendment, I found it interesting that the Court's definition seems to say (paraphrased in plain terms): In order to ensure that a truly free country remains so, it is important that all able-bodied men in the country be allowed to own tools of violence and employ them in a structured fashion.
This seems to imply that the Constitution forbids that the Federal Government hold this monopoly on violence for the specific purpose of ensuring the continued freedom of the Country's inhabitants.
There are some arguments that the 2nd Amendment's purpose was mainly to allow people to defend themselves, from whatever threat, through the use of these tools of violence.
Does the US Federal Government currently hold this monopoly?
Have they always, since its founding, held this monopoly?
If the answers to these two questions are different, what has changed this and why?