The US faces a new and bitter legal struggle over abortion after a federal judge barred the government from enforcing legislation outlawing so-called partial birth abortions - hours after the measure was signed into law by President George Bush.
Both sides in the abortion debate were yesterday digging in for a fight that will almost certainly only be resolved by the Supreme Court. The controversy is likely to become part of the 2004 election campaign, pitting the broadly pro-abortion rights Democrats against the social and religious conservatives who form a key part of Mr Bush's political constituency.
The measure is aimed at the procedure known as "intact D&X", which is used in the second or third trimester of a pregnancy. The procedure, which is used in only a tiny proportion of abortions, is defined in the bill as when a foetus is partly delivered and then killed, when either the head or body is "outside the body of the mother".
Twice in the past decade a Congress controlled by Republicans passed similar legislation which was vetoed by the then President Bill Clinton, mainly because there was no provision for exceptions where the health of the mother was seriously endangered.
That omission was cited by Richard Kopf, a Nebraska federal district judge, when he issued the blocking order on Wednesday on the ground that the new law might be unconstitutional because it cited only ill-defined "legislative findings" that the barred procedure was "never necessary" to preserve the pregnant woman's health. Judge Kopf suggested the new law was "highly suspect" and possibly in conflict with a 2000 ruling in the Supreme Court that overturned similar measures outlawing partial birth abortions passed by several states, among them Nebraska.
The margin on that occasion was 5-4, the most slender possible. Right-to-choose advocates fear a vacancy on the court would give Mr Bush the chance to replace a pro-abortion rights justice with a conservative, tipping the balance in favour of the new law.
The pro-abortion lobby believes that the ban will forbid other common procedures. It also believes it is intended by opponents of abortion as step towards their real goal: overturning the Supreme Court's historic 1973 judgment in Roe vs Wade, enshrining a woman's legal right to an abortion.
Federal judges in New York and California are examining separate requests for a halt to the measure, which President Bush described as "a terrible form of violence against children who are inches from birth while the law looks the other way".
Kate Michelman, head of Pro-Choice America, said the bill came at "a very serious and decisive moment" in which the future of legal abortion was at stake. Howard Dean, a doctor and front-runner for the 2004 Democratic nomination, said he was "outraged that President Bush has decided that he is qualified to practise medicine".