As the founding fathers made clear in the Decelaration of Independence in 1776:
"When in the corse of human events, it becomes neccessary for the people to dissolve the political bands which have connected them with one another, and to assume the powers of the earth, the seperate and equal station to which the Laws of Nature and of Nature's God entitles them, a decent respect of the opinions of mankind requires that they should declare the causes which impel them to the seperation."
"...Governments are instituted among Men, deriving their just powers from the consent of the governed, that whenever any Form of Government becomes destructive to these ends, it is the Right of the People to alter or abolish it, and institute new Government..."