Factbox: Major U.S. Supreme Court abortion rights cases

(Reuters) – The U.S. Supreme Court’s key rulings on abortion, dating to the landmark 1973 decision that legalized the procedure nationwide, have long provoked social, religious and political tensions.

As the court majority became more conservative over the decades, it set standards that enhance states’ ability to regulate abortion. Yet even in the most recent rulings, extending to 2007, there have never been five votes on the nine-member court to reverse the fundamental right to abortion.

Here is a look at the court’s major abortion rulings.

Roe v. Wade, 1973, 7-2 vote

The court rules that a woman’s constitutional right to privacy protects her decision to end a pregnancy, and only a compelling state interest can justify regulating abortion. The decision institutes a three-part legal test, connected to a nine-month pregnancy and a fetus’ viability, that gives states more latitude for regulation with each trimester.

Planned Parenthood of Southeastern Pennsylvania v. Casey, 1992, 5-4 vote

The court affirms the right to abortion. Rather than the trimester framework, the test is whether a government regulation imposes an “undue burden” on a woman seeking an abortion by creating a “substantial obstacle” to the procedure before the fetus develops to the point at which it becomes viable.

Stenberg v. Carhart, 2000, 5-4 vote

The court decides that a Nebraska ban on a late-term procedure critics call “partial birth abortion” violates a woman’s right to abortion. The procedure, known medically as “intact dilation and extraction,” involves a physician removing most of the fetus intact rather than dismembering it. The justices fault the Nebraska ban, similar to laws in a majority of the states at the time, for its ambiguity about precisely what type of medical procedure is prohibited and for lacking an exception for the health of the mother.

Gonzales v. Carhart, 2007, 5-4 vote

The court decides that a federal Partial Birth Abortion Act, involving the same type of procedure as in the Nebraska dispute and without an exception for the woman’s health, is constitutional. The majority distinguishes the ruling from the 2000 case by noting that Congress developed findings that the procedure would never be necessary for the health of the mother. Another factor in the reversed course was that in 2000, Justice Sandra Day O’Connor had voted to strike down the partial-birth ban. She was succeeded by Samuel Alito in 2006, and in 2007 he cast the fifth vote in favor of the ban.

Whole Woman’s Health v. Hellerstedt, 2016, ruling pending

The court takes up a challenge brought by abortion providers to provisions in a 2013 Texas law that impose regulations on abortion doctors and clinic facilities. The challengers say the regulations are medically unnecessary and intended to shut abortion clinics. The state says the law protects women’s health. The court is due to issue its ruling on Monday. One provision requires doctors to have a type of formal affiliation called “admitting privileges” at a hospital located not more than 30 miles (48 km) from the abortion clinic. The other establishes minimum standards for abortion facilities equivalent for those applying to “ambulatory surgical centers” in the state. These requirements for costly, hospital-grade facilities apply to numerous building characteristics.

(Compiled by Joan Biskupic in Washington; Editing by Will Dunham)