It would be the principle of "popular sovereignty" that asserts that citizens not politicians or government officials hold ultimate authority, which was a major component of the Enlightenment.
There are actually numerous answers to this question. One could be the Supreme Court Justices since they serve lifetime or until they decide to retire.
In Order to form a more perfect Union that means to have states staying together, so they can operate as a single nation.
Because there armY hand more experience