The bill got final Congressional approval a few minutes after midnight, and was signed quickly shortly after 1 a.m. by President Bush, who had flown back to the White House from his Texas ranch to be ready to act quickly because Schiavo has been without nutrition or water since Friday, when her feeding tube was removed in compliance with a Florida court order.
The bill Mr. Bush signed into law could lead to the reinsertion of Terri Schiavo's feeding tube, at least temporarily, while the battle over her condition and fate enters yet another phase of a continuing legal battle.
The House passed the legislation on a 203-58 vote after calling lawmakers back for an emergency Sunday session for a debate that stretched past midnight.
The Senate approved the bill Sunday by voice vote.
The legislation, said President Bush, "will allow Federal courts to hear a claim by or on behalf of Terri Schiavo for violation of her rights relating to the withholding or withdrawal of food, fluids, or medical treatment necessary to sustain her life."
"In cases like this one, where there are serious questions and substantial doubts, our society, our laws, and our courts should have a presumption in favor of life," Mr. Bush continued, in a written statement issued as he signed the bill.
"This presumption is especially critical for those like Terri Schiavo who live at the mercy of others," said the president. "I appreciate the bipartisan action by the Members of Congress to pass this bill. I will continue to stand on the side of those defending life for all Americans, including those with disabilities."
Schiavo's parents, who believe she has the potential to get better, have many supporters - scores of whom have been protesting and holding a vigil outside the hospice where Schiavo has gone without nourishment since Friday, when her feeding tube was removed in compliance with a court order sought by her husband, Michael.
An attorney for Schiavo's parents says every federal judge who could hear the case has agreed to take it on an emergency basis once the bill passed by Congress becomes law. A judge will be chosen at random, and the attorney hopes to immediately have Schiavo taken to a hospital to have the tube reinserted.
CBS News Legal Analyst Andrew Cohen says lawyers for both sides are likely to be in federal court, filing papers to support their arguments, before the end of the day.
"The most important thing to remember and understand about all of this is that it is still up to the courts to decide what will happen to Terri Schiavo," says Cohen. "Schiavo's parents certainly will ask immediately to have her feeding tube reinstated and for a new round of hearings to determine whether she legally can be kept on life support indefinitely. Michael Schiavo almost certainly will ask the judge to declare the new law unconstitutional and to block its enforcement."
"It is possible that a federal judge will order Terri Schiavo's feeding tube to be reinserted, even for a short time, even if he or she ultimately decides that the new law is unconstitutional," says Cohen. "It would be hard to argue against the pressing need to keep her alive until this new round of federal litigation is resolved."
"We feel every moment is urgent, we are considering every second as precious in terms of saving Terri," said David Gibbs II, an attorney for Schiavo's parents, Bob and Mary Schindler.
Schiavo's husband has expressed outrage at congressional intervention in what he maintains is a private right-to-die battle with Schiavo's parents. The family has been fighting for years over whether she should be permitted to die or kept alive by the feeding tube.
"For Congress to come in and interfere in a personal family matter is outrageous. They can do it to me, they'll do it to every person in this country. And they should be ashamed of themselves. Leave my wife alone. Leave me alone. Take care of your own families," he told CBS News.
Outside the hospice, a subdued crowd of about 50 people prayed and sang behind signs bearing such slogans as "Let Terri Live" and "President Bush Please Save Terri." One man played "Amazing Grace" on a trumpet, as a pickup truck pulled a trailer bearing 10-foot-high replicas of the stone Ten Commandments tablets and a huge working version of the Liberty Bell.
Will Svab, 24, of Seminole, held a 6-foot plastic foam spoon bearing the words "Please Feed Terri."
"We're hopeful," he said of the recent developments in Congress. "In our faith it's Palm Sunday. It brings us hope that something good will happen."
The 41-year-old woman's feeding tube was removed Friday on a Florida judge's order. Schiavo could linger for one or two weeks if the tube is not reinserted — as has happened twice before, once on a judge's order and once after Gov. Jeb Bush passed "Terri's Law," which was later declared unconstitutional.
Terri Schiavo suffered severe brain damage in 1990 when her heart stopped briefly because of a chemical imbalance. She can breathe on her own, but has relied on the feeding tube to keep her alive.
Doctors say she is in a persistent vegetative state with no hope of recovery. Her husband says she would not want to be kept alive in that condition, but her parents insist she could recover with treatment.