Yes- only for terrible crimes, followed subsequently by execution
Yes, for terrible crimes, followed subsequently by life imprisonment
Never, under any circumstances.
There are many situations where criminal justice and the legal system are basically irrelevant or not applicable. For example if it involves illegalities or in basically forgotten communities.
If a low rent man beats a low rent hooker or barfly, the law is likely to do nothing, basically can't be reported, and even if police/DA do anything, it will be so trivial as to not serve any deterrent value to others. However, if it understand in advance that the result is to get the hell beat out of him it does have a deterrent value. The "legal system" of even our civilized society operates possible as much or more on that level of justice.
It has nothing to do with government and the thugs (not bullies, thugs keep bullies in check) are just part of the alternative system. Who is "qualified" is who is capable.
You are mixing domestic criminal justice issues with military/terrorism issues. Those are very different questions in my opinion.