WASHINGTON — A dejected Sen. Lindsey Graham blasted the Supreme Court's ruling Thursday on Guantanamo Bay detainees, calling it "dangerous and irresponsible."

The South Carolina Republican, who's also a military lawyer and a colonel in the Air Force Reserve, helped craft the Military Commissions Act and had confidently predicted that it would pass high court muster.

The Supreme Court repudiated Graham in a 5-4 decision, ruling that the 270 alleged terrorists being held at the U.S. military prison in Cuba have a constitutional right to challenge their detentions in federal courts.

"The court's ruling makes clear the legal rights given to al Qaida members today should exceed those provided to the Nazis during World War II," Graham said. "Our nation is at war. It's truly unfortunate the Supreme Court did not recognize and appreciate that fact."

The high court's decision was its third ruling in four years against the special powers that President Bush has claimed the executive branch has to detain and try suspected terrorists since the Sept. 11, 2001, attacks.

With Graham in the lead, Congress passed the Military Commissions Act in September 2006 after an earlier Supreme Court ruling that the Bush administration couldn't set up a new system for prosecuting alleged terrorists without congressional approval.

The fresh Supreme Court decision is a major blow for Graham politically, eviscerating a law that he recently cited as one of the three achievements of his first Senate term that he was most proud of.

"To the extent that Lindsey Graham wanted to get the federal courts out of the process (of prosecuting detainees) altogether, this ruling is an absolute loss for him, and it's one that Congress can't go back around," said Thomas Crocker, a University of South Carolina law professor.

Graham said he'd explore the possibility of drafting a constitutional amendment "to blunt the effect of this decision."

Any constitutional amendment would be unlikely to move in Congress during the waning months of a lame-duck presidency, however, and at the height of a campaign for the White House.

Graham's talk of a constitutional amendment indicated how little room the Supreme Court has left him, Sen. John McCain — the presumptive Republican presidential nominee — and Bush in their long-standing effort to create a separate trial system outside the federal courts for alleged terrorists.

Graham said that the law gave terrorism suspects at Guantanamo adequate protections, including the power to ask tribunals to review their detainments and to challenge convictions before the U.S. Court of Appeals for the District of Columbia Circuit.

With the Supreme Court now giving detainees full access to the federal courts, Graham warned that "some of the most liberal district courts in the country will have an opportunity to determine who is a threat to the United States."

"Federal judges will now be in charge of the day-to-day military prisons and the interrogation of prisoners," Graham said. "This will empower activist lawyers and interest groups to intervene in basic military matters for the first time in history."

Crocker of USC, though, said Graham was exaggerating the effects of the ruling.

"The court does not claim it has the power to make military decisions, but it does claim the power granted it under the Constitution to hear certain claims properly brought under the writ of habeas corpus," Crocker said.