The abortion issue has been revisited several times since Roe, most famously in Webster v. Reproductive Health Services (1989) and Planned Parenthood v. Casey (1992).
Webster (a 5-4 decision) upheld major parts of a Missouri abortion law that prohibited the use of public facilities or the participation of public employees in abortions, and required doctors to test the viability of the fetus before an performing any abortion.
Justices William Rehnquist, Byron White and Anthony Kennedy said they would allow restrictions on abortion, but only if the restrictions had a rational basis. More important, the three conservative justices said, a compelling government interest need not be required to justify restrictions on abortion. That was a blow for anti-abortion forces.
Then came the Casey ruling, in which the justices outlined their views on Roe. The decision (also 5-4) reaffirmed the heart of Roe while giving states the power to regulate procedures so long as they did not impose an "undue burden" on a woman's right to abortion. The standard: Undue burden exists if "the purpose and effect is to place substantial obstacles in the path of a woman seeking an abortion before the fetus attains viability." The ruling left supporters on both sides of the issue dissatisfied, feeling it was ambiguous.
Justice Sandra Day O'Connor joined neither opinion, saying there was nothing in it to justify reconsidering Roe. Nevertheless, Blackmun wrote, "the right to reproductive choice" was in danger of being overturned.
Another legacy of Roe: The head-counting of justices on the court, a what-if scenario that could lead to the overturning of Roe. The current 5-4 conservative majority might shift in either direction if two or more justices leave the bench in the next few years, as is widely expected.
In the meantime, conservatives in Congress have promised to push for tougher restrictions on access to abortion, though many political experts say the goal is not necessarily aimed at overturning Roe.
They found success five years ago when the justices, in a 5-4 ruling, upheld a federal ban on a controversial late-term procedure, rejecting concerns the law didn't take into account the physical safety of the woman.
The procedure -- called "partial birth abortion" by its critics -- is typically performed in the middle-to-late second trimester. The legal sticking point was that the law lacked a "health exception" for women who might suffer serious medical complications, something the justices have said in the past is necessary when considering abortion restrictions.
The swing vote, as in previous cases, came from Kennedy. In angry dissent, Justice Ruth Bader Ginsburg, then the lone woman on the high court, called the majority's conclusions "alarming" and said they "cannot be understood as anything other than an effort to chip away a right declared again and again by this court, and with increasing comprehension of its centrality to women's lives."
Ginsburg has long been a leading voice for gender equality. Ironically, some of the opposition to her 1993 nomination to the high court came from feminists, who did not like her criticism over the legal reasoning of Roe.
She believed a more gradual liberalization to abortion would have kept the issue back in the states, avoiding the social and political upheaval that has been part of Roe's legacy. The law on abortion was evolving at the time of Roe, Ginsburg recalled in 2005. "The Supreme Court stopped all that by deeming every law -- even the most liberal -- as unconstitutional. That seemed to me not the way courts generally work."
But Ginsburg, in her rulings, has upheld a woman's reproductive choice. "When government controls that decision for her, she's being treated as less than a full adult human being responsible for her own choices," she said during her confirmation.
If there is one overriding legacy of the Roe decision, it may be that it opened and expanded the debate on the rights of women, sexuality, health care, and medical decisions. Issues like cloning, stem cells, and fetal research have become part of the national lexicon. As significant as it was, Roe v. Wade was only the beginning of the battle.