The Constitution also provides us a mechanism to reverse tyranny; however, I believe we are well past the point of effectively utilizing that mechanism.
Good, but you forgot the fourth branch - the states themselves.
I can just imagine the horror and disgust the framers of the Constitution would show us for letting the federal government become such an powerful oppressive 'organism'. I believe no one would have voted for Constitution if they could have seen into the future and see what we would have to deal with today.
Today, the Constitution has been turned upside-down, inside-out, and backward. It is now used to limit our freedoms and expand the all powerful federal government's. Exactly the opposite intended by it.
But when those who's only goal is more power, what should we expect?