In Texas, abortion providers were in court this week asking a federal judge to stop a new law that they say would close more than half of the state's abortion facilities by imposing costly new standards.
In Alabama, a federal judge ruled Monday that a law requiring doctors at abortion clinics to have hospital admitting privileges was unconstitutional. A similar law in Wisconsin is under court review.
And in Idaho and Arkansas, state officials are asking federal appellate judges to reverse lower court rulings that struck down laws sharply narrowing the time frame in which women can get abortions.
These and other cases result from the vast array of abortion restrictions approved by Republican-controlled legislatures in recent years. The laws take several different forms, including restricting the availability of abortion medication, curtailing insurance coverage for abortion, imposing new requirements on abortion clinics and providers, and prohibiting most abortions after 20 weeks.
Here's a look at some of major types of laws, and how they figure in pending legal cases:
HOSPITAL ADMITTING PRIVILEGES
In more than a dozen states, opponents of abortion have introduced bills requiring that doctors at abortion clinics have admitting privileges at nearby hospitals. Such laws could force the closure of clinics whose doctors - in some cases from out-of-town - are unable to get admitting privileges.
The laws have taken effect in some states, including Missouri, Texas, Utah and Tennessee, but have been blocked, at least temporarily, in other states, including Mississippi, Alabama and Wisconsin.
Admitting-privileges laws are scheduled to take effect Sept. 1 in Louisiana and Nov. 1 in Oklahoma. Abortion-rights groups say the laws will leave only one clinic open in Oklahoma and force the closure of at least three of Louisiana's five clinics, including those serving New Orleans, leaving clinics only in the northwestern corner of the state.
The measure debated this week in federal court in Austin, Texas, was part of a sweeping anti-abortion law passed last year by the GOP-controlled Legislature. It would require all abortion clinics to meet the same standards as ambulatory surgical centers, entailing costs that abortion supporters say could not be met by 18 clinics. Such closures would leave many women along the Texas-Mexico border with at least a four-hour drive to the closest U.S. abortion provider.
Similar measures have been pushed in other states, including Virginia, which, under Republican Gov. Bob McDonnell adopted regulations last year requiring existing abortion clinics to meet the same strict building standards as new hospitals. McDonnell's Democratic successor, Terry McAuliffe, has directed the state health board to complete a review of the regulations by Oct. 1 and has appointed five new board members who support abortion rights.
Supporters of the regulations say they are intended to protect women's health; opponents say the aim is to put clinics out of business.
Under the U.S. Supreme Court's 1973 Roe v. Wade ruling establishing a nationwide right to abortion, states were permitted to restrict abortions after viability - the point when the fetus has a reasonable chance of surviving under normal conditions outside the uterus. The ruling offered no legal definition of viability, saying it could range between 24 and 28 weeks into a pregnancy.
In recent years, abortion opponents in several states have challenged this aspect of Roe by proposing laws narrowing the time frame for legal abortions. The strictest laws - in North Dakota and Arkansas - were struck down by federal judges, and both states are pursuing appeals. North Dakota's law would ban abortions as soon as a fetal heartbeat can be detected, which can be as early as six weeks into a pregnancy. The Arkansas law would ban abortions after 12 weeks.
A more common approach, tried by about a dozen states, is to enact a law banning abortions after 20 weeks of pregnancy on the disputed premise that a fetus can feel pain at that stage. Some of those laws have taken effect; others have been blocked in Arizona, Georgia and Idaho. The Idaho attorney general's office is working on an appeal of the ruling striking down Idaho's ban.
Another line of attack by abortion opponents has targeted the increasingly common option of terminating a pregnancy via medication rather than surgery.
In Arizona, a federal appeals court panel has blocked rules released in January by the state health department that would ban women from taking the most common abortion-inducing drug - RU-486 - after the seventh week of pregnancy. The state is fighting in court to put the rules into effect.
In Indiana, a federal judge has blocked a law that would have required clinics offering nonsurgical abortions using the abortion pill to meet the same standards as those performing surgical abortions.
While abortion restrictions have surfaced in state legislatures for decades, the trend has accelerated in recent years, with some of the new laws - such as the admitting-privileges measures - threatening to close most or all abortion clinics in a given state.
"It used to be a brick-by-brick approach, and now they're throwing up the wall all at once, so you can't get over it no matter how high you jump," said Jennifer Dalven, director of the American Civil Liberties Union's Reproductive Freedom Project.
Many of the recent laws are modeled on proposals by Americans United for Life, which depicts abortion as a danger to women's health. The aim of the tighter restrictions, says AUL's president, Charmaine Yoest, is "protecting women and their unborn children from a largely unregulated, unrestricted, and unrepentant abortion industry."
Abortion-rights supporters insist that the procedure is safe and were heartened by Monday's ruling in Alabama, where U.S. District Judge Myron Thompson rejected the state's argument that admitting privileges should be required as a protection for women. He said the law, by forcing the closure of clinics in three cities, "would impose significant obstacles, burdens and costs for women."
Given that federal judges have blocked admitting-privileges laws in some states and upheld them in others, it's possible a case may reach the U.S. Supreme Court. In its 1992 Planned Parenthood v. Casey ruling, the high court said states could impose some restrictions on abortion, but not an "undue burden" on women's rights to the procedure.
Nancy Northup, president of the Center for Reproductive Rights, said the bills requiring admitting privileges or setting costly standards for abortion clinics were imposing an undue burden by forcing some clinics to close.
"The Supreme Court will have to make clear their decision in Casey doesn't mean politicians have free rein to lie about their motives and intrude on women's decisions to end their pregnancy," she said.
Ovide Lamontagne, general counsel of Americans United for Life, agreed that the split lower court decisions might lead to a Supreme Court case. He expressed hope that the high court would view the state laws as promoting "commonsense health and safety standards."