On January 22, 1973, the Supreme Court voted to protect a woman's right to have an abortion in the early stages of her pregnancy. Before the landmark Roe v. Wade decision, abortion was banned in two-thirds of states, and an estimated 1.2 million women a year resorted to illegal, often dangerous back-alley abortions.

Now, 39 years later, conservative lawmakers are making unprecedented moves toward reversing Roe v. Wade, and the legality of abortion is as precarious as it's ever been.

By all accounts, 2011 saw a remarkable wave of legislative attempts to limit women's reproductive rights. Some states brazenly challenged Roe with laws that would never have been considered before evangelical and Tea Party candidates swept state legislature elections in 2010. At least six states -- Alabama, Louisiana, North Dakota, Ohio, Mississippi and Oklahoma -- seriously considered laws that would ban abortion altogether.

None of these measures passed, in some cases because anti-abortion activists worried that they were so extreme that the inevitable court battles would only end up reaffirming Roe, but the states did enact more subtle limits on abortion that had a higher likelihood of standing up in court.

So-called "fetal pain" bills swept the Midwest in 2011, as five states joined Nebraska in banning abortions after 20 weeks of gestation. These bills directly challenge the Supreme Court precedent set forth in the 1992 case Planned Parenthood v. Casey, which effectively amended Roe to say that states cannot ban abortion before the fetus is considered viable outside the womb -- usually around 22 to 24 weeks.

As state lawmakers successfully passed a record number of previsions that restrict access to abortion, women's rights activists have had to pick and choose their court battles, based on which laws most egregiously fly in the face of Supreme Court precedent and place an undue burden on a woman's ability to seek abortion in her state.

The Center for Reproductive Rights (CRR) managed to block a law in Kansas that regulated abortion clinics so strictly that they would be forced to shut their doors. The group is also challenging a ban on safe, early-pregnancy medication abortions in North Dakota and laws in Texas and North Carolina that force doctors to show a woman her ultrasound image and play her the fetal heartbeat before she can have an abortion. The Texas law is the only one that has made it up to a U.S. Court of Appeals; 5th Circuit Chief Judge Edith Jones, a conservative, wrote the opinion upholding the law.

As states continue to lay the groundwork for challenging and ultimately reversing Roe, the CRR, the American Civil Liberties Union and other reproductive rights advocates are gearing up for many more court battles in 2012. A number of states are now considering "fetal personhood" measures, which would give legal personhood rights to fertilized eggs and ban abortion even in cases of rape, incest, or when the mother's life is in danger.

Ohio is also considering a "heartbeat bill," which would ban abortions as soon as the fetal heartbeat is detectable. This can occur as early as six weeks into gestation -- often before the woman even realizes she is pregnant.

"Many states are already preparing for the day after Roe," said Kristi Hamrick, a spokeswoman for Americans United for Life. "Abortion will become an issue decided by state legislators more in tune with the views of their constituents, rather than a few, robed individuals."

The fate of the state laws, if and when they reach the Supreme Court, will likely depend on which Justice Anthony Kennedy shows up.

There's the Justice Kennedy of Casey v. Planned Parenthood, who came to Roe's aid with vaunted libertarian language when abortion rights were directly under attack.

And then there's Justice Kennedy of the Carhart cases of 2000 and 2007, who sided with the Court's conservatives to uphold bans on late-term abortion procedures. They were successful the second time around, after Justice Samuel Alito replaced Justice Sandra Day O'Connor in 2006.

"It's anyone's guess as to which Justice Kennedy it will be," said Professor Helen Knowles of Whitman College and author of the book The Tie Goes to Freedom: Justice Anthony M. Kennedy on Liberty.

"Whether it will be the more libertarian, individual choice jurist that was present in Casey or the more conservative jurist who [in the late-term abortion cases] clearly saw individual choice needing to be restrained," Knowles told HuffPost, depends on how the state laws are presented to the Court.

"I don't think any full-frontal challenge to Roe is going to make much headway with Kennedy" given his vote in Casey, Knowles said. Indeed, Kennedy remains the only justice still sitting on the Court from that landmark case's five-member majority. As Casey's flame-keeper and -- since O’Connor’s retirement -- its chief interpreter, he wields the power to define abortion rights. But with that power comes the responsibility he shouldered in Casey to take those rights seriously, however narrowly he construes them and despite his known personal opposition to abortion.

Rather than take on Roe itself, then, Knowles said, "the way that pro-life groups would make greater headway is by defending parts of the regulation that come close to the central holding of Roe, but not too close.”

And the new spate of state laws appear designed to test just where Kennedy draws his red line. The fetal pain and fetal heartbeat laws play on the same sense of sympathy for the unborn that inspired Kennedy’s disgust with late-term abortion procedures. But when voting to uphold bans on some types of those procedures, Kennedy made clear that his doing so rested mostly on the actual or theoretical availability of other procedures by which a woman could still exercise her right to obtain an abortion before her fetus reaches viability. Fetal pain and fetal heartbeat laws -- like the even more extreme personhood laws -- that leave women with no alternatives risk triggering Kennedy’s sense of responsibility for Roe’s safekeeping.

Still, Kennedy believes that “the State’s constitutional position in the realm of promoting respect for life is more than marginal.” For that reason, laws that dictate how, and not whether, abortions are performed -- such as the Texas ultrasound law -- may pass muster with Kennedy. In his 2000 opinion, Kennedy noted that Casey reversed earlier decisions striking down laws requiring doctors “to inform the woman of the status of her pregnancy, the development of her fetus, the date of possible viability, the physical and emotional complications that may result from an abortion, and the availability of agencies to provide assistance and information.”

“Rather than exalting the right of a physician to practice medicine with unfettered discretion,” Kennedy wrote, the question courts must consider in abortion cases is whether the state had "substantial and objective medical evidence" to justify the law.

Justice Kennedy's pivotal role, however, could be entirely canceled out if a Republican takes the White House in 2012 and one of the Court's staunchly pro-choice members -- such as the 78-year-old Justice Ruth Bader Ginsburg -- leaves the bench.

All four of the GOP presidential candidates who are still in the race have said that they would work to reverse Roe v. Wade, leaving the issue up to the states to decide, and former House Speaker Newt Gingrich, Rep. Ron Paul (R-Texas), and former Sen. Rick Santorum (R-Pa.) all said at a "personhood" forum Wednesday night that they would support granting legal rights to human embryos. Those three candidates also signed Susan B. Anthony List's pro-life leadership pledge, swearing to nominate only conservative justices to the federal bench and to "select only pro-life appointees for relevant Cabinet and Executive Branch positions.

Opposition to Roe v. Wade, however, is nothing new for today’s more extreme anti-abortion movement. When Kennedy -- along with fellow Reagan appointee O’Connor and George H.W. Bush appointee David Souter -- thwarted Roe’s reversal in 1992, the GOP committed itself to putting reliably pro-life judges on the federal bench. And George W. Bush did so upon taking office, stacking the appeals courts with judges capable of taking out Roe once and for all if tapped to take a seat alongside the Court’s four-justice conservative bloc.

"The presidency is critical in 2012," said Nancy Keenan, president of NARAL Pro-Choice America. "When the average age of retirement on the Supreme Court has been about 79, and we have three justices 75 and older, elections matter. Who's going to sit in that space? Will it be someone who respects freedom and privacy?"