WASHINGTON — The Supreme Court told the high court of Oklahoma on Thursday to clarify a new state law restricting the use of the RU-486 abortion pill, possibly setting the stage for a ruling on how far states can go in regulating the practice of abortion.

Legislators in several states, including Oklahoma, have passed laws to strictly regulate the practice of abortion. Among them are measures that require all women seeking abortions to undergo an ultrasound test.

But the Oklahoma Supreme Court blocked these laws from taking effect last year, saying they conflicted with a 1992 U.S. Supreme Court decision on abortion.

The Oklahoma attorney general appealed, and on Thursday, the justices, in their last meeting until late September, sent the case back and ordered the Oklahoma Supreme Court to answer two questions about the law before they consider the appeal.

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The Supreme Court wants to know if the Oklahoma law “prohibits the use of misoprostol to induce abortions, including the use of misoprostol in conjunction with mifepristone according to a protocol approved by the Food and Drug Administration.” The high court also wants to know if the law stops “the use of methotrexate to treat ectopic pregnancies,” which is when an embryo implants somewhere outside of the uterus.

The state said its aim was to protect the health of women by ensuring that the abortion pills are used in accord with federal protocols. But the legal challenge brought on behalf of doctors and patients says the law, if put into effect, would prevent women from using these approved medications to induce abortion.

Usually, two drugs are prescribed in combination for women who seek an abortion in the first weeks of a pregnancy. One, mifepristone, is better known as RU-486. The second drug, misoprostol, is usually taken later, and they can induce an abortion up to nine weeks into pregnancy.

The Center for Reproductive Rights, which is challenging the law, said: “Medical abortion is a simple, safe procedure that allows a woman to choose to end a pregnancy in a private, noninvasive way in consultation with her doctor. Anti-choice activists are doing everything they can to stop it.”

At issue ultimately is the meaning of the high court’s 1992 decision in Planned Parenthood v. Casey. That case upheld a woman’s right to choose abortion but said states may regulate the practice, so long as they do not put an “undue burden” on patients or their doctors.

Oklahoma Attorney General Scott Pruitt asked the high court to allow his state’s Ultrasound Act to go into effect, but the justices took no action on that request before leaving on their summer recess.

Material from The Associated Press is included in this report.