WASHINGTON — President Bush early today signed emergency legislation allowing the parents of Theresa Schiavo, a severely brain-damaged Florida woman, to continue their battle to keep her alive.

In a rare Sunday session, lawmakers raced to pass the bill allowing a federal judge to override a Florida judge’s order to disconnect a feeding tube from Mrs. Schiavo, 41, on Friday. The House passed the bill 203-58 early today after the Senate passed the measure by unanimous consent yesterday afternoon. House Democrats had delayed the vote until after midnight to allow a debate on the issue.

Members of the House of Representatives were called back from recess around the country and the world to cast their votes.

Mr. Bush cut short a stay at his ranch in Crawford, Texas, to return to the capital so he could sign the bill into law in the early hours this morning.

“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 said in a statement after signing the bill.

Rep. Peter King, a Republican of Long Island, said he agreed with Mr. Bush.

“The presumption should always be on the side of life. Especially in this case, when there is such a clear dispute between the husband and parents on her intentions,” Mr. King said.

But several New York Democrats disagreed and rushed back to the capital to vote against the measure.

“This is the arrogance of unchecked power, the contempt for families and for the sanctity of marriage,” said Rep. Jerrold Nadler, a Democrat of Manhattan, in a floor statement.

“It would place a federal judge in the middle of a case, after state courts, doctors, family members, counselors, and clergy have struggled with it for years. After everything is over, we’re putting one of those “unelected federal judges” my colleagues always denounce right in the middle of it,” he said.

Rep. Anthony Weiner, a Democrat of Queens, said, “This is a difficult but settled case. Congress should not be substituting our judgment here.”

Mr. Weiner accused Republicans of “outrageously politicizing” a private tragedy, and he pointed to a report in the Washington Post yesterday that disclosed the existence of an internal memo distributed to Republican senators that described the case as a “great political issue” that could pay dividends with Christian conservatives in the midterm elections.

“For a bunch of conservatives, the DeLay Congress certainly doesn’t seem to respect the rights of state courts and rights of individual families to resolve these issues without their intervention,” he said.

The federal legislation is the latest twist in a lengthy legal battle between Mrs. Schiavo’s husband, Michael, who argues that his wife expressed a wish to be allowed to die under such circumstances, and her parents, Robert and Mary Schindler, who doubt his account.

Mrs. Schiavo suffered severe brain damage 15 years ago as a result of a chemical imbalance. Seven years later, her husband asked that she be allowed to die. Mr. Schiavo had since moved in with another woman with whom he has two children, and Mrs. Schiavo’s family has said they question his motives in seeking her death.

The law Mr. Bush signed today allows Mrs. Schiavo’s parents to sue on her behalf in federal court and argue that removing the feeding tube had violated her constitutional rights.

Under the new law, a federal judge in Florida will review the case anew, without regard of the findings of the previous judges who have already reviewed the case.

“The bill guarantees a process to help Terri, but does not guarantee a particular outcome,” said the majority leader in the Senate, Senator Frist of Tennessee.

Mrs. Schiavo’s parents and siblings thanked the Congress and the president and called on opponents to not politicize their tragedy.

“It is astonishing to me that as a society we are allowing people to be starved to death,” said her brother, Robert Schindler, speaking on the Fox News Channel.

Michael Schiavo condemned the federal government for interjecting itself in his wife’s case. “I am outraged, and I think every American in this country should be outraged that the government is trampling a personal and family matter that was adjudicated for seven years,” Mr. Schiavo said.

Doctors have found that Mrs. Schiavo is in a “persistent vegetative state” and is not aware of her surroundings. But her parents and siblings counter that she recognizes them when they approach her, and have said she can feel emotions.

The Supreme Court declined to hear an appeal in the case on Thursday.

Mr. Frist said he expected a judge to issue an injunction requiring that the feeding tube be reinserted so Mrs. Schiavo can survive until the legal proceedings can take place.

The law states explicitly that it does not create any precedent that could be applied to other cases.

But Democrats who opposed the law warned it would open the floodgates to congressional interference in numerous family feuds.

Republicans argued the measure was necessary to ensure that none of Mrs. Schiavo’s rights under the federal Constitution were violated by state courts.

Senator Martinez of Florida said the judge’s ruling last week was a “death warrant” for Mrs. Schiavo, and compared the legislation’s added layer of judicial review to the appeals that are available to prisoners on death row.

The law also contains a commitment that Congress will examine the status of legal rights of incapacitated individuals who are unable to make decisions concerning the provision or withdrawal of life-sustaining treatment.

The chairman of the House Judiciary Committee, Rep. James Sensenbrenner, a Republican of Wisconsin, said, “Broad consideration of this issue is necessary to ensure that similarly situated individuals are accorded the equal protection under law that is both a fundamental constitutional right and an indispensable ingredient of justice.”

During floor debate in the House that began at 9 p.m. last night, Republicans emphasized that Mrs. Schiavo was not dependent on artificial life support, and that some doctors believe her quality of life could be improved with therapy.

But Democrats stressed that all the facts of the case had been reviewed in court, and that politicians should not interject themselves into a single case because they disagree with the outcome.

“A much-loved disabled woman has been ordered to die by starvation and dehydration,” said Rep. Christopher Smith, a Republican of New Jersey. “Disabled people deserve what everyone else deserves: to have their fundamental human rights protected and properly asserted.”

Rep. Jim Davis, a Democrat of Florida, who has followed the case for years, said lawmakers were casting votes in a case they were not familiar with.

“Let’s keep in mind that neither this House nor Senate has had a single hearing, has heard from a single witness, has provided any meaningful opportunity for the public to participate in this very important debate,” he said.

Mr. Davis said the family had the opportunity to raise federal constitutional issues in the state trial. “This bill does not create any new rights, it simply creates a new judge in an attempt to achieve a different result, or to delay a different decision,” he said.

Rep. Ginny Brown-Waite, a Republican of Florida, who spoke against the measure, said, “It is important to know that the Schindler family members stated that even if Theresa had told them of her intention to have artificial nutrition withdrawn, they would not do it.”