As for the fact that most abortions are performed early in pregnancy, and the majority’s assertion that alternatives to the prohibited procedure are available for later in pregnancies, Justice Ginsburg said adolescents and indigent women have more trouble obtaining an abortion early, so today’s ruling could put them at a disadvantage.

Justice Ginsburg also took issue with language in the law finding a “consensus” that the banned procedure is never necessary.

But the majority said disagreements within the medical community constituted no obstacle to the 2003 law. “The court has given state and federal legislatures wide discretion to pass legislation in areas where there is medical and scientific uncertainty,” Justice Kennedy wrote. “Medical uncertainty does not foreclose the exercise of legislative power in the abortion context any more than it does in other contexts.”

Today’s decision gave the anti-abortion forces what they had hoped for with the more conservative makeup of the high court since Justice Alito replaced Justice Sandra Day O’Connor. Abortion opponents are sure to be pleased by some of the language in Justice Kennedy’s opinion, including his observation that “the government may use its voice and its regulatory authority to show its profound respect for the life within the woman.”

The ruling is surely not the last word on abortion, either legally or politically, and it immediately reflected the deep divides that have long characterized the issue. Republicans praised the decision, while Democrats denounced it.

“I applaud the court’s decision to uphold the ban on partial-birth abortion,” said Senator Mel Martinez of Florida, chairman of the Republican National Committee, adding that the ruling “spoke highly of society’s core values to protect the sanctity of life.”

President Bush called the ruling “an affirmation of the progress we have made over the past six years in protecting human dignity and upholding the sanctity of life.”