Confronting new doubts raised by government memos, the Senate voted Wednesday to make clear that the United States will not use torture (search) against detainees.

The voice vote, on an amendment to a defense spending bill, followed disclosures last week of Bush administration memos contending the government may not be bound by international anti-torture principles in the war against terror.

"The world is watching us," said the legislation's sponsor, Sen. Richard J. Durbin (search), D-Ill. "They are asking whether the United States will stand behind its treaty obligations in the age of terrorism."

The measure says the United States "shall not engage in torture or cruel, inhuman or degrading treatment ... a standard that is embodied in the U.S. Constitution and in numerous international agreements which the United States has ratified."

The amendment also would require the secretary of defense to issue guidelines to ensure troops comply with the standards and report to Congress on any suspected violations. There is no equivalent legislation in the House defense authorization bill and the two chambers would have to decide whether to include it in the final version.

Memos from Justice Department and White House lawyers have argued that a president can order torture or any other interrogation methods as part of his powers as commander in chief of the military. One, an August 2002 memo from then-Assistant Attorney General Jay Bybee, says torture "may be justified" in some interrogations of terrorist suspects.

President Bush himself last week sidestepped a question about whether he thought torture was immoral, saying that his instructions were "to adhere to law."

"We do not condone torture and the president has never authorized the use of torture," Trent Duffy, White House deputy press secretary, said Wednesday.

But rights groups and other critics say the memos laid the legal foundation for Iraqi prisoner abuses were aimed mainly at showing that international treaties banning torture do not apply to Al Qaeda (search) and Taliban (search) prisoners.

"In the age of terrorism, we may be tempted by the notion that torture is justified. Our enemies certainly do not respect any rules in their relentless quest to kill Americans," Durbin said. "But this nation's commitment to principle, even during difficult times, is what distinguishes us from the terrorists we fight."

Michigan Sen. Carl Levin, the most senior Democrat on the Senate Armed Services Committee, said the measure also protects American soldiers.

"If we lower our standards, it is only going to encourage others to engage in the torture or mistreatment of American prisoners of war in enemy custody," he said.

In other business related to the prisoner controversy, the Senate, by a 54-43 vote, defeated legislation that would have forced the Defense Department to cut back on its use of civilian contractors, who are accused along with military troops of having mistreated Iraqis at a prison outside of Baghdad.

It voted 97-0 to extend use of two U.S. criminal statutes overseas, a measured aimed at better prosecuting companies that overcharge or use other fraudulent schemes to profit unduly from war contracts. Senators rejected 52-46 a measure that would have made war profiteering a new federal crime subject to up to 20 years in prison.