Washington ? The ban on certain abortions that President Bush signed into law this week differs somewhat from an earlier state ban the Supreme Court already has found unconstitutional. But lawyers say it’s probably not different enough to pass muster at the high court.

Both sides in the contentious and emotional debate predict the justices will have the last word on the new law, the most significant national restrictions on abortion since the Supreme Court’s 1973 Roe v. Wade decision established a woman’s right to the procedure.

Three years ago, the court relied in part on Roe in a 5-4 ruling that a Nebraska law similar to the new federal statute suffered two major constitutional flaws.

First, the court said, that law was too imprecise. Second, and more important, the high court objected that it lacked an exception to protect a pregnant woman’s health. If a doctor found that the procedure was the safest way to end a pregnancy, it should not be off-limits, the court found.

The new law bars certain second- and third-trimester abortions in which a fetus is partially delivered before being killed, usually by having its skull punctured.

The new law only goes halfway to satisfying the court’s objections, several lawyers said. It includes a graphic definition of the procedure to be banned but it contains no specific exception to protect a woman’s health. Instead, Congress said its own findings showed the abortion method was never medically necessary.

Lawyers predict at least one trial before a federal judge and a ruling from a federal appeals court before the case reaches the Supreme Court, probably at least a year from now.

Legal experts expect the law will be overturned.

“I cannot think of another piece of constitutional litigation where the ultimate outcome is more predictable than this,” said David Garrow, a constitutional law professor at Emory University who has written extensively about abortion law.