A federal appeals court ruled today that state laws in Arkansas, Iowa and Nebraska banning the most controversial form of late-term abortion are unconstitutional because they place an "undue burden" on women seeking to end their pregnancies and would prohibit some of the most commonly used abortion procedures.

Upholding injunctions issued by lower courts against laws in the three states that ban what opponents call "partial-birth" abortions, the three-judge panel of the 8th U.S. Circuit Court of Appeals said the laws are so broadly written that they potentially cover all abortions.

Since the three unanimous opinions are the first appellate court rulings on the constitutionality of partial-birth abortion bans, they are likely to have wide reverberations, not only in other states where such laws are being challenged in federal courts but also in Congress, where the language of a pending partial-birth abortion bill is almost identical to that of the Iowa and Nebraska bans.

A more immediate effect could be felt in Missouri, where the state legislature last week overrode Democratic Gov. Mel Carnahan's veto of the state's partial-birth abortion ban. A federal judge has temporarily blocked enforcement of the ban and scheduled a trial for March 27 on a request by Planned Parenthood of St. Louis for a permanent injunction. Although the Missouri law differs in approach from other partial-birth abortion bans, opponents believe yesterday's ruling would affect it as well.

"This means the Missouri case won't go to trial; it'll go to summary judgment," said Janet Benshoof, president of the New York-based Center for Reproductive Law and Policy. "These decisions reaffirm that the Constitution still applies to women and their health care."

However, abortion opponents said the partial-birth issue is far from being resolved and predicted that the state bans would be ruled constitutional in further appeals.

"U.S. Supreme Court, here we come," said Janet Parshall, spokeswoman for the anti-abortion Family Research Council in Washington. "This is a classic case where politics is on a collision course with judicial reality."

Thirty states have passed partial-birth abortion bans, and in 18 of them, federal courts have blocked the laws with either permanent injunctions or temporary restraining orders. In Virginia, a permanent injunction against the state ban has been stayed, pending a ruling on the ban by the 4th Circuit Court of Appeals.

The key language in all three rulings today was nearly identical. In the Arkansas case, for example, the appellate judges said in a 10-page opinion that "the central difficulty with the [state ban] is that it covers too much."

The judges said the law's language would would ban more than just partial-birth abortions -- in which a pregnant woman's cervix is dilated to allow the fetus to partially emerge, after which the fetus is killed by inserting a suction tube into its skull and removing the contents. They said it would also ban two other abortion methods protected by the U.S. Supreme Court in the landmark Roe v. Wade decision: the dilation and evacuation procedure, which is the most common procedure used in second-trimester abortions, and the suction-curettage procedure, which is the most common method in first-trimester abortions.

Noting that the District Court had held the ban unconstitutional because it was overly vague, imposed an undue burden on pregnant women and did not adequately protect their health and lives, Judge Richard S. Arnold wrote, "We agree that the [ban] imposes an undue burden on women seeking abortions and therefore hold the act unconstitutional." The judges did not rule on the other grounds because they said it was unnecessary to do so.

Benshoof, whose center has brought 14 court challenges against partial-birth abortion bans including the three cases decided today, said that the issuance of today's narrowly written opinions by an appellate panel generally considered to be relatively conservative "strips away a fraud perpetuated in all of these legislatures and shows that these laws don't just cover late-term abortions."

Kate Michelman, president of the Washington-based National Abortion and Reproductive Rights Action League, called the rulings "a profound statement about how wrong anti-abortion extremists are to use the partial-birth strategy as a mask for their attempts to overturn Roe v. Wade." She added that the rulings should "send a message to Congress" to reject the current federal partial-birth abortion bill, which was introduced after President Clinton vetoed a similar 1997 bill.

However, Mary Spaulding Balch, state legislative director for the Family Research Council, noted that there are a half-dozen other appeals pending in partial-birth abortion cases and at least seven states where bans have not been challenged in federal court.

"Ultimately, it will go to the U.S. Supreme Court," Balch said. "The American people support the belief that that particular procedure has to be banned. And we will let the Supreme Court decide."