“It gets controversial when a president simply states that he’s acting under the power granted to him by the Constitution and laws of the United States,” says Phillip J. Cooper, author of the book “By Order of the President: The Use and Abuse of Executive Direct Action.”

Bush invited controversy with his aggressive use of “signing statements,” written pronouncements during bill signings that explain the president’s view of a law – including at times the constitutionality of some aspects of it. In his first presidential campaign, Obama decried Bush’s practice, but as president, he has continued it.

In their use of executive orders, Bush and Obama are virtually tied: In his first five years in office, Bush issued 165 orders, versus 167 by Obama. But a bean-counting approach doesn’t capture the scope of a president’s approach to executive power.

“It’s really the character of the actions, and their subject,” says Jonathan Turley, a constitutional scholar at George Washington University in Washington, D.C. “In my view, Obama has surpassed George W. Bush in the level of circumvention of Congress and the assertion of excessive presidential power. I don’t think it’s a close question.”