Maryland's highest court yesterday upheld a lower court ruling that Prince George's County Executive Lawrence Hogan exceeded his authority when he attempted to stop county-run hospitals from performing abortions.

In a unanimous opinion written by Chief Judge Robert C. Murphy, the Court of Appeals said Hogan usurped the power of the county council when he issued an executive order barring abortions from being performed at two county hospitals except to save the life of the mother. The court said Hogan also may have usurped the power of other executive officers by issuing the order.

The executive's role in implementing county laws and policies does not "constitute a grant of unbridled authority permitting him to usurp, nullify, or supersede at his pleasure functions and duties committed by law to other executive branch officers," Judge Murphy wrote.

The ruling dealt the final blow to Hogan's attempts to ban abortions in the county's two hospitals. After Hogan issued his order on Aug. 11, 1980, citing his personal moral beliefs, the American Civil Liberties Union filed suit on behalf of a 18-year-old Catholic woman, identified only as Jane Doe, seeking to block the order. A second suit against the order was filed three weeks later on behalf of doctors at Prince George's General.

The two suits later were combined, and Prince George's County Circuit Court Judge Howard S. Chasanow ruled on Dec. 17, 1980, that Hogan had exceeded his authority in issuing the order. As a result of his decision, abortions continued to be performed at both Greater Laurel-Beltsville Hospital and Prince George's General Hospital.

Hogan appealed Judge Chasanow's ruling to the appeals court, which heard the case the first week of September.

While the case was pending, the county executive attempted to obtain County Council approval of legislation enforcing the abortion ban, but the bill was defeated when the council deadlocked over it.

A spokeman for the American Civil Liberties Union immediately praised yesterday's ruling. "We're delighted that the highest court of Maryland has reaffirmed the importance of legal limitations on executive authority and ruled that the county executive does not have the power to impose his personal moral beliefs on the people of Prince George's County."

County Attorney Robert Ostrom spoke for Hogan and said, "I would assume that Mr. Hogan is disappointed that the court did not overturn the lower court's ruling. He set the policy and he would like to see it implemented."

Yesterday's decision stressed that Hogan had exceeded his executive authority as well as attempted to take over a policy-making legislative function. "Even assuming that he exercised executive rather than legislative power, we think its promulgation in this case is beyond that vested in the county executive by the charter," the court wrote. The court also criticized Hogan for making his decision without consulting hospital administrators and the hospital commission, who also are executive officers or allowing them to have a public meeting on the issue.