TOPEKA, Kan. (AP) _ The state's highest court has limited the power of a grand jury investigating Wichita abortion provider Dr. George Tiller.

The Supreme Court on Tuesday refused to strike down a state law allowing citizens to petition for grand juries. Abortion opponents used that statute last year to force Sedgwick County to convene one.

But in doing so, the court ruled unanimously that the grand jury's power is not unlimited.

At issue were subpoenas the grand jury issued to Tiller and Attorney General Steve Six, seeking medical records from Tiller's clinic. Tiller and Six wanted the subpoenas quashed or modified.

The court didn't do that, but it did set guidelines for determining whether the subpoenas should be enforced. It returned the case to a lower court.

(Copyright 2008 by The Associated Press. All Rights Reserved.)