A federal judge Tuesday ruled that President Bush's Partial-Birth Abortion Ban Act (search) is unconstitutional and infringes on a woman's right to choose.

The ruling applies to the nation's 900 or so Planned Parenthood (search) clinics and their doctors, who perform roughly half of all abortions in the United States.

U.S. District Judge Phyllis Hamilton's (search) ruling came in one of three lawsuits challenging the legislation Bush signed last year.

"The act poses an undue burden on a woman's right to choose an abortion," she wrote.

Federal judges in New York and Nebraska also heard challenges to the law earlier this year but have yet to rule.

"Partial-birth abortion is lawful in the United States from and after today," said Fox News' senior judicial analyst Andrew Napolitano. Even "if a judge in New York finds there's nothing wrong with the statute, it's still banned."

In a statement, the Bush re-election campaign said: "Today's tragic ruling upholding partial birth abortion shows why America needs judges who will interpret the law and not legislate from the bench. ... John Kerry's judicial nominees would similarly frustrate the people's will and allow this grotesque procedure to continue."

Raw Data: Planned Parenthood v. Ashcroft (FindLaw pdf)

Stephanie Cutter, spokeswoman for Massachusetts Sen. John Kerry, said the presumptive Democratic presidential nominee voted to restrict late-term abortions when the measure contained a "clear exception for life or health of women."

"However, George Bush pushed through a different piece of legislation that failed to protect the health of women and that is what the court struck down today," she said. "When John Kerry is president he will appoint judges that are committed to upholding the Constitution, not pursuing an ideological agenda."

Bush signed the bill in November, saying "a terrible form of violence has been directed against children who are inches from birth while the law looked the other way."

In the banned procedure — known as intact dilation and extraction to doctors, but called partial-birth abortion by opponents — the living fetus is partially removed from the womb, and its skull is punctured or crushed.

Justice Department attorneys argued that the procedure is inhumane, causes pain to the fetus and is never medically necessary.

"The department will continue to devote all resources necessary to defend this act of Congress, which President Bush has said 'will end an abhorrent practice and continue to build a culture of life in America,'" said Justice spokeswoman Monica Goodling. "The Justice Department has worked hard during these trials to fulfill the goal of the president to protect innocent new life from the practice of partial-birth abortion, and we will continue to do so."

Planned Parenthood lawyer Beth Parker welcomed the ruling, saying it sends a "strong message" to Attorney General John Ashcroft and the Bush administration "that the government should not be intruding on very sensitive and private medical decisions."

Republicans on Fire

Republican lawmakers decried Tuesday's ruling.

"As a physician, this procedure is shameful, I think, is outside of the bounds of the practice of medicine. It is a barbaric procedure, and it should be banned," Senate Majority Leader Bill Frist, R-Tenn., told reporters Tuesday.

"I'm very disappointed in the decision today, and I think that ultimately that decision will be overturned. And I hope that it will be overturned."

Bush-Cheney re-election campaign chairman Marc Racicot said the ruling is a prime example of "why America needs judges who will interpret the law and not legislate from the bench."

"A majority of Americans oppose partial-birth abortion, and Judge Hamilton's decision flies in the face of Congress passing and President Bush signing legislation banning such horrible acts of violence," Racicot said in a statement.

Racicot said Tuesday's ruling is a "stark reminder" of the choice Americans must make in November when they go to the polls and vote for Bush or Kerry as the next president.

"John Kerry's judicial nominees would similarly frustrate the people's will and allow this grotesque procedure to continue," Racicot said. "Americans from across the political spectrum oppose partial-birth abortion because they support a culture of life, but John Kerry returned to the Senate last year to oppose the partial-birth abortion ban."

Abortion proponents, however, argued that a woman's health during an abortion is more important than how the fetus is terminated, and that the banned method is often a safer solution that a conventional abortion, in which the fetus is dismembered in the womb and then removed in pieces.

The measure, which President Clinton had twice vetoed, was seen by abortion rights activists as a fundamental departure from the Supreme Court's precedent in Roe v. Wade (search). It shifted the debate from a woman's right to choose and focused on the plight of the fetus.

Abortion advocates said the law was the government's first step toward outlawing abortion. Violating the law carries a two-year prison term.

New York, Nebraska Decisions Expected Soon

Late last year, Hamilton, a Clinton appointee, and federal judges in New York and Lincoln, Neb., blocked the act from being enforced pending the outcome of the court challenges. They began hearing testimony March 29.

Doctors have construed the Supreme Court's decision in Roe. v. Wade to mean they can perform abortions usually until the 24th to 28th week after conception, or until the "point of viability," when a healthy fetus is thought to be able to survive outside the womb. Generally, abortions after the "point of viability" are performed only to preserve the mother's health.

Doctors at about 900 abortion clinics practice under the Planned Parenthood umbrella, performing about half the nation's 1.3 million annual abortions.

The Nebraska and New York cases are expected to conclude within weeks.

The New York case was brought by the National Abortion Federation (search), which represents nearly half the nation's abortion providers. The Nebraska case was brought by a few abortion doctors.

The U.S. Supreme Court had overturned a Nebraska partial-birth abortion law because it did not allow the banned procedure even when a doctor believes the method is the best way to preserve the woman's health.

But Congress simply declared that the procedure is never medically necessary — and during weeks of testimony, doctors testifying for the government stressed that same point — claiming that there are better alternatives to the method, and that it may even be harmful to women.

Witnesses for the abortion providers, however, testified in all three trials that the banned method is often preferred and sometimes necessary to preserve a woman's health.

Congressional sponsors said the ban would outlaw only 2,200 or so abortions a year. But abortion providers testified the banned method can happen even at times when doctors try to avoid it, such as when they attempt to remove the fetus from the womb in pieces.

Because of the possibility that the fetus may partially exit a woman during an otherwise legal procedure, abortion rights advocates said the law could ban almost all second-trimester abortions, which account for about 10 percent of all abortions in the United States.

Fox News' Anna Stolley, Ellen Uchimiya and The Associated Press contributed to this report.