Feb. 24 (Bloomberg) -- The South Dakota Legislature planned a final vote today on adopting an abortion ban that would create a constitutional challenge of the U.S. Supreme Court's 1973 Roe v. Wade decision establishing the right of women across the U.S. to medically terminate pregnancies.

The state's House of Representatives was due to vote this afternoon on legislation that would be the first attempt in a state to outlaw all abortions since a 1989 Supreme Court ruling affirmed states' rights to regulate the procedure, said Nancy Keenan, president of NARAL Pro-Choice America, a Washington group that supports legalized abortion.

That ruling, known as the Webster case, spawned a host of attempts to restrict abortion. South Dakota's legislation could become a test case for states wanting to ban abortion, said Tony Perkins, president of the Washington-based Family Research Council, which opposes abortion.

``This will become a political battle in every state that wants to consider banning abortion,'' said Keenan.

A legal challenge may take years to wind its way through the courts, creating the possibility that the anti-abortion faction on the U.S. Supreme Court will be stronger than it is now, said Vikram Amar, a law professor at the University of San Francisco in California.

There's no certainty the recent additions of Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr. will produce a 5-4 majority to overturn Roe v. Wade, Amar said. A court challenge may be needed just to see where the current justices stand.

Testing Court

``Unless a legislature passes a bill testing the opinion, there is no way to know if the court's opinion has changed,'' said Amar, a scholar in constitutional law. ``They can't signal a change of attitude without a vehicle for it.''

South Dakota lawmakers introduced the bill Jan. 24 after President George W. Bush's nominations of Roberts and Alito.

The House passed its first version 47-22 on Feb. 9 and an amended bill passed the state Senate two days ago. The amendment changes wording though not the ban on abortions, which has no exceptions for rape, incest of the mother's health.

Under South Dakota law, Governor Mike Rounds would have five days from when he receives the bill to decide whether to sign the measure. The Republican governor declined through spokesman Mark Johnston to say what he will do.

The U.S. Supreme Court Feb. 21 said it would hear the Bush administration's appeal of a ruling that found the 2003 Partial Birth Abortion Ban Act unconstitutional because it doesn't make an exception when a mother's health is at risk.

To contact the reporter on this story: Darrell Preston in Dallas at dpreston@bloomberg.net.

Last Updated: February 24, 2006 14:05 EST