Topeka ? The state’s highest court is allowing a grand jury to keep investigating one of the few U.S. doctors who performs late-term abortions but is limiting its power to subpoena his patients’ records.

The Supreme Court refused Tuesday to strike down the law abortion opponents used to force Sedgwick County to convene the grand jury to investigate whether Dr. George Tiller violated state restrictions on abortion. The high court also declined to quash subpoenas it issued to Tiller and Attorney General Steve Six.

But in its unanimous ruling, the Supreme Court said there are limits on the grand jury’s power. The justices set guidelines, returned the case to district court and ordered the presiding judge to follow the new standards in determining whether the subpoenas should be enforced.

“The court should satisfy itself that the grand jury has not engaged in an arbitrary fishing expedition and that the targets were not selected and subpoenas issued out of malice or with intent to harass,” Justice Lee Johnson wrote for court. “If so, the court should quash the subpoenas.”

Abortion opponents generally were pleased with the ruling, though some said they had to review the court’s decision thoroughly. Anti-abortion groups had feared that the Supreme Court would quash the subpoenas or even dissolve the grand jury.