President Bush is seen after signing the Military Commissions Act of 2006, Oct. 17, 2006

U.S. President George Bush has signed into a law a series of new rules for interrogating suspected terrorists and bringing them to trial. Critics say the measure violates defendants' civil liberties.

The law authorizes a previously-secret interrogation program by the Central Intelligence Agency that President Bush says is one of the nation's most important tools in fighting terrorism.

"This bill spells out specific, recognizable offenses that would be considered crimes in the handling of detainees so that our men and women who question captured terrorists can perform their duties to the fullest extent of the law," Mr. Bush says.

The Bush administration first acknowledged that program six weeks ago when it transferred suspects from CIA custody to a military detention center at Guantanamo Bay, Cuba.

Leading members of the president's political party raised concerns about the treatment of those held by the CIA, blunting Republican hopes of using the debate to portray opposition Democrats as weak on terror.

The new law is something of a compromise as it protects detainees from abuses including rape, torture, and practices deemed cruel and inhuman.

President Bush says it reflects both the spirit and the letter of America's international treaty obligations, including the Geneva Convention.

"The United States does not torture," Mr. Bush says. "It is against our laws and it is against our values.  By allowing the CIA program to go forward, this bill is preserving a tool that has saved American lives."

The law also authorizes military commissions that President Bush proposed following the September 11, 2001 terrorist attacks in New York and Washington.

The U.S. Supreme Court ruled that President Bush could not create those commissions by Executive Order.  Instead they must be explicitly authorized by Congress.

Now that they are, President Bush says it sends a clear message to terrorists that America will answer brutal murder with patient justice.

"These military commissions will provide a fair trial in which the accused are presumed innocent, have access to an attorney, and can hear all the evidence against them," Mr. Bush says. "These military commissions are lawful, they are fair, and they are necessary."

Critics of the law say it gives prosecutors too much power by allowing coerced testimony as evidence and denying defendants the ability to challenge their detention.

In a written statement, Senator Patrick Leahy, the ranking Democrat on the Judiciary Committee, called the bill signing a sad day because the law, in his words, undercuts American freedoms and is being used by the president for political purposes to avoid accounting for what Leahy calls the administration's unlawful actions.