The battle over partial birth has set off one of the fiercest political clashes since Roe v. Wade. The new law is the first to criminalize a specific abortion technique–and the first time Congress has stepped so squarely into the doctor’s office to outlaw a medical procedure. The measure bars “an overt act” that “will kill the partially delivered living fetus.” After an emotional final day of debate, even 18 senators who generally support abortion rights voted for the ban, which passed 64-34–a bipartisan win for abortion foes. “We have just outlawed a procedure that is barbaric, that is brutal, that is offensive to our moral sensibilities and that is out of the mainstream of the ethical practice of medicine today,” said Senate Majority Leader Bill Frist, a surgeon, declaring victory after the vote.

Though the ban is clearly a major public-relations setback for abortion rights, its real effect is less clear. Abortion-rights supporters argue that the new law is not only bad for womens’ health, but virtually identical to the Nebraska statute the court struck down. “We will be in court before the ink is dry on the president’s signature,” says Planned Parenthood president Gloria Feldt. Still, the defeat could have an upside. “It will be a wake-up call to pro-choice Americans that this administration and this Congress are serious about rolling back a woman’s right to choose,” says Naral Pro-Choice America president Kate Michelman, who hopes to make abortion a central issue in next year’s presidential race.

Under President Clinton, Congress twice passed a partial-birth ban, but Clinton vetoed it both times because it lacked an exception allowing the method to be used to preserve a woman’s health. Since 1995, 31 states have passed their own bans. But judges have consistently struck them down. The biggest blow came from the Supreme Court. Agreeing with Carhart, the justices ruled 5-4 that the Nebraska law was too vague and could ban all abortions after the first trimester, placing “an undue burden” on a woman’s right to an abortion. Also, the justices said, the law did not allow the technique to be used even when it was best for a woman’s health. Authors of the new bill took note. They tinkered with the description of the procedure to make it more specific, though critics charge it’s still too broad. But instead of a health exception–which they feared would create a loophole–lawmakers included nearly six pages of congressional “findings” on why the method is never necessary for a woman’s health. Abortion-rights supporters will seek an immediate injunction in federal court–a request that’s likely to be granted and keep the law from taking effect.

The case will likely land in the Supreme Court in the next few years. But court watchers doubt the justices–especially swing voter Sandra Day O’Connor–will view the new law favorably. “The absence of a health exception is inescapably fatal,” says Emory legal historian David Garrow. Abortion foes have one other hope: if O’Connor or another pro-Roe justice retires, a re-elected Bush could fill a vacancy with a staunch abortion opponent who could tip the balance in their favor. But if the ban loses in the courts, what seemed like a turning point could become just another skirmish in the abortion wars.