The US Supreme Court on Thursday agreed to wade into a dispute over an Oklahoma regulation of the abortion-inducing drug RU-486.

In a brief order, the justices agreed to take up the case, and then asked the Oklahoma Supreme Court to determine whether the disputed state law bars the application of certain drugs used in chemically induced abortions.

The court said that further proceedings in the case would be reserved pending receipt of a response from the Supreme Court of Oklahoma.

The action came in an appeal filed on behalf of the Oklahoma attorney general asking the justices to reinstate an Oklahoma law regulating RU-486 abortions that was struck down by the state high court in December.

The law sought to limit chemically induced abortions to a protocol of procedures that critics said were outdated and would effectively ban the procedure.

In his brief to the court, Oklahoma Solicitor General Patrick Wyrick asked the justices to examine whether the Oklahoma Supreme Court ruled correctly when it invalidated the 2011 state law that had mandated that all drug-induced abortions in the state follow a specific protocol.

Under the law, abortion providers were required to follow instructions approved by the Food and Drug Administration back in 2000 when chemically induced abortions were first approved.

The Oklahoma Coalition for Reproductive Justice challenged the law, arguing that the 2000 protocol had since become obsolete and had been replaced by newer time-tested procedures and doses that were safer, more effective, and less expensive.

The new procedures allow a woman to self-administer a second drug at home rather than in a clinic. They also extended the effective use of the chemically induced abortion process from 49 days into the pregnancy to 63 days.

Mr. Wyrick said the state legislature was justified in favoring the older protocol because eight otherwise healthy young women have died from bacterial infections following chemically induced abortions using one of the newer protocols. In contrast, he said, no women have died following use of the older protocol.

The state solicitor general said the Oklahoma law merely regulates the manner in which abortion-inducing drugs were administered and does not ban the use of those drugs.

A state court judge struck the statute down, because it was deemed to impose a substantial obstacle to a woman obtaining an abortion.

The judge concluded in part that the state law “is so completely at odds with the standard that governs the practice of medicine that it can serve no purpose other than to prevent women from obtaining abortions, and to punish and discriminate against those who do.”

On appeal, the Oklahoma Supreme Court ruled that the state law was unconstitutional under the US Supreme Court’s abortion precedent, Planned Parenthood of Pennsylvania v. Casey.

Wyrick said the state high court was wrong. “House Bill 1970 does not prohibit any type of abortion,” he said in his brief to the court. “It merely requires that abortion inducing drugs be administered in the manner approved by the FDA.”

Michelle Movahed, a lawyer with the Center for Reproductive Rights, which is representing the Oklahoma Coalition, said in her brief that the Oklahoma law goes too far in restricting access to abortions.

She said the Oklahoma legislature had enacted several laws in recent years seeking to restrict abortions in the state. The state Supreme Court has upheld some, but overturned others as too restrictive.

“The statute at issue here effectively bans all abortions performed using medication (rather than by surgery), no matter how early in the pregnancy,” Ms. Movahed wrote in her brief.

“The statute’s only practical consequence is to force a woman who wishes to terminate a pregnancy to undergo a surgical procedure even though a safe, effective, non-invasive, and widely used alternative is available,” she said.

Movahed said the newer protocols were legal and common. She said nationwide protocols other than FDA approved protocol from 2000 are being used in at least 96 percent of chemically induced abortions.

The case is Terry Cline v. Oklahoma Coalition for Reproductive Justice (12-1094).