The Bush administration has asked the US Supreme Court to reinstate a ban on a procedure that critics call "partial birth" abortions, setting up a showdown that could be decided by the president's new choice for the court.
The appeal, which had been expected, follows a two-year legal fight over the law. Abortion is one of the most volatile issues in US politics and Christian conservatives opposed to abortion are some of President George W. Bush's strongest supporters.
An appeals court in St. Louis said this summer that the ban on late-term abortions is unconstitutional because it makes no exception for the health of the woman.
The Supreme Court has already scheduled arguments in another abortion case, involving New Hampshire's parental notification statute. That case also asks whether the law is unconstitutional because it lacks an exception allowing a minor to have an abortion to protect her health in the event of a medical emergency.
The court should deal with both cases, Solicitor General Paul Clement said in the appeal, which was filed last Friday and released on Monday.
The earliest that justices could review the federal law, known as the federal Partial-Birth Abortion Ban Act, is next spring. By then, the court could have two new members.
The Senate is expected to vote this week on Bush's nomination of John Roberts to be chief justice.



