Washington ? President Bush has vetoed only one piece of legislation during more than five years in office, but he has issued more than 800 challenges to bills that he has signed into law with formal “signing statements,” more than all of his predecessors combined.

Now, however, a task force of the American Bar Assn. has concluded that the president’s stream of signing statements pose a dangerous challenge to the constitutional checks and balances central to governmental power in the United States. One of the signing statements reserves the right to torture detainees held in the war on terrorism.

The ABA report, being released today, calls on Congress to exert more oversight and empower the courts to review presidential signing statements asserting the president’s right to “ignore or not enforce laws.” If unchecked, ABA President Michael Greco said in a prepared statement, the presidential use of signing statements “raises serious concerns crucial to the survival of our democracy.”

This hardly is the first report or court ruling to raise concerns about Bush’s exercise of executive authority, with the Supreme Court recently overruling the president’s decision to try detainees at Guantanamo Bay, Cuba, with military tribunals without the approval of Congress. The president has asserted sweeping wartime powers since the terrorist attacks of Sept. 11, 2001.

The White House maintains that Bush is not attempting to make any grab for increased executive power, and that Bush is not flouting the laws that he signs with the issuance of signing statements, but rather raising constitutional concerns.

“The president does not, and the administration does not, refuse to carry out the laws that have been passed by Congress and signed into law by the president,” said White House spokesman Tony Snow, maintaining that Bush is not engaging in any “civil disobedience.”

“In the context of trying to preserve and protect and defend the Constitution … there will be places within signing statements – caveats – where he has reservations,” Snow said. “It is not unusual – although we have done it more than previous administrations – to list those reservations, if nothing else, as markers, for issues that may later rise to be points of controversy.”

But this does not square with many of the administration’s own signing statements, according to Neal Sonnett, a Miami lawyer, former U.S. attorney and chairman of the ABA task force making the report today.

“It’s clear that a large number of the signing statements that have been issued by this administration claim the authority to disregard the law,” Sonnett said. “This president is not the first president to do that. But he clearly has escalated the practice to what the task force believes is a dangerous new high. That has an impact on the separation of powers, and if it’s left unchecked it could do damage to our system and to the Constitution.”