Powers once granted are almost impossible to take back.
After 13.5 years, there is more than enough evidence for reasonable people to conclude that the presidencies of George W. Bush and Barack H. Obama are easily the most destructive in U.S. history.
When historians speak of failed presidencies or weak presidencies, they are typically referring to presidencies characterized by uneven leadership, petty corruption by self-serving cronies or in extreme cases such as the Nixon presidency, abuses of executive power.
But weak or failed presidencies are not destructive to the rule of law and the foundations of the nation. The failed president leaves office and the basic structure of the nation continues: the rule of law, the balance of powers and a free-market economy.
A destructive president weakens or corrupts these core structures in favor of executive-branch powers, and passes these unconstitutional powers to the next executive for further expansion.
The Bush and Obama presidencies have effectively dismantled the rule of law and the Constitution by invoking essentially unlimited executive powers in the name of "national security:" we the citizens of the U.S. can now be accused of violating secret laws, be indicted in secret, tried in secret and sentenced to life in prison based on evidence fabricated in secret, i.e. declaring unclassified documents classified after the fact to incriminate and imprison whistleblowers.
How is this any different from totalitarian fascist regimes?