For more than two decades, the ruling in the Roe vs. Wade case, which established a woman's constitutional right to an abortion, has been a rallying point for millions. Opponents and supporters continue to fight for their cause.

The opinion has turned political novices into activists and has been a litmus test for Supreme Court nominees and political appointees. It has been a cornerstone of campaigns at every level nationwide. It also has led some to commit deadly violence.

Defining moment in history

"Roe vs. Wade was a defining moment in our history. It has touched all of our lives in one way or another," said Gloria Feldt, president of the Planned Parenthood Federation of America. "It has fundamentally altered the legal, medical and political landscape of this country."

Today, the ruling remains legally complicated, emotionally explosive and politically divisive. The controversy shows no signs of abating as new issues have surfaced, including proposed bans on late-term abortions and a push for new laws to protect the rights of fetuses.

Even Jane Roe, the Texas woman who sued for a woman's right to have an abortion, has remained in the fray. The woman, Norma McCorvey, is now in her 50s, a grandmother and vehemently anti-abortion -- to the consternation and skepticism of pro-choice organizations. She said she became a Christian in 1995 and regrets her role in the case.

"I signed an affidavit that brought the holocaust of abortion onto this nation," said McCorvey, who has written a book about her life and conversion. "I'm just really grateful I'm in the kingdom of God now, and all is forgiven."

A deeply divided public

Public opinion on abortion, however, has not changed dramatically during the last 33 years. Since the first polls were done in the wake of the 1973 ruling, Americans have held deeply contradictory views on the issue: Most think abortion should be legal, but most also believe it is murder.

"The public is at once pro-choice and pro-life," said Karlyn Bowman, a resident fellow at the American Enterprise Institute who studied polls on the issue. "Americans want to keep abortion legal and at the same time support restrictions on its use."

New strategy by protestors

What has changed is the nature of the conflict. Since the Supreme Court reaffirmed Roe in 1992, opponents have all but conceded defeat at directly attacking it. As a result, they are seeking to chip away, fighting for bans on late-term abortions, pushing for greater state regulation of abortions and encouraging malpractice lawsuits against abortion providers.

Foes also point to new developments in the law that give fetuses greater protection. In some states, a woman can be prosecuted for harming her fetus by drinking or taking drugs. That same woman, however, could have chosen to abort her fetus legally.

"You cannot have abortion on demand as a fundamental right and at the same time start criminalizing fetal damage caused by drug use or alcohol use," said Jay Sekulow, chief counsel for the American Center for Law and Justice.

Complicating matters are advances in medical technology, which mean doctors can operate on fetuses in the womb and deliver them earlier.

Blackmun's choice

Justice Harry Blackmun could not have possibly foreseen these issues when he crafted the majority opinion in Roe vs. Wade, which ruled a Texas statute unconstitutional because it prohibited abortion.

Blackmun spent the rest of his tenure on the court defending Roe and a woman's right to an abortion, but his majority decision has been harshly criticized by legal analysts and people on both sides of the abortion issue.

It is thought of by many as a poorly reasoned exercise in judicial overreaching that usurps the legislative branches of government.

"It's an outrageous constitutional ruling," constitutional scholar Bruce Fein said. "The court is supposed to be interpreting the Constitution, not writing a treatise on the evolution of abortion."

There were two dissents to Roe, each of which foreshadowed the criticism to come. Justice Byron White wrote that the court had no grounds for making such a decision, calling it an "exercise of raw judicial power." Justice William Rehnquist, who later became chief justice of the United States, also dissented and would vote to overrule the decision.

Indeed, the Rehnquist Supreme Court, while refusing to overrule Roe, seemed to want to distance itself from the decision. The ruling's reasoning was never mentioned in other opinions, and it never was extended to other areas such as physician-assisted suicide. Even abortion-related opinions, such as one written by Rehnquist in 1989, don't mention the constitutional right that was the basis for Roe.

Roe vs. Wade challenged

The biggest threat to Roe came in 1992 when the court decided Planned Parenthood vs. Casey, a case challenging Pennsylvania restrictions on abortion. Abortion supporters feared the court would use the case to overrule Roe, but the court, in a 5-4 decision, reaffirmed it.

Even so, the court upheld several restrictions, including a 24-hour waiting period. It also adopted a new standard for determining when laws restricting abortion violate the Constitution. The court now asks whether a law would impose an "undue burden" on a woman seeking an abortion before the fetus is viable.

Most states have adopted some restrictions on abortion. Thirty-nine states have passed laws that require minors to get the consent of a parent or judge before getting an abortion but the law is not being inforced in at least nine states.