The U.S. Court of Appeals strongly criticized St. Elizabeths Hospital yesterday for failing to take adequate security measures to confine criminal defendants committed there by court order because they are insane.

Ruling in the case of Dwayne White, who stabbed his wife 55 times with a pair of scissors in 1979 after walking off the hospital grounds, a three-judge panel said the federally operated mental hospital was "clearly negligent" in fulfilling its "duty to protect the public . . . [by taking] steps to prevent the escape of its dangerous patients."

The panel ordered U.S. District Judge Joyce Hens Green to reopen a $1 million lawsuit brought in 1981 by Genoa White, Dwayne White's wife, which Green previously had dismissed.

Dr. Harold Thomas, the hospital spokesman, said yesterday he could not comment on whether the decision would be appealed, but he said the hospital plans no changes in its security policies.

All persons are allowed to enter and leave three gates to the St. Elizabeths grounds without any security checks during daytime hours, Thomas said, although there are security checks at some hospital buildings.

At present the hospital has about 270 patients committed by criminal court orders, including presidential assailant John W. Hinckley Jr., out of a total patient population of about 1,600.

"The philosphy here is one of treatment and rehabilitation," Thomas said. "The patients must be given some responsibility for themselves. We don't expect everyone here to be locked up forever.

"Security is at the ward door." Thomas continued, "When a person is allowed off the ward and onto the grounds, it is based on a clinical evaluation.

"Our fence is a border marking. There is no barbed wire . . . . This is not a prison. This is a hospital. It would be impossible to police the fence line and the gates to see who comes and who goes . . . . And clinically we don't see a need to do that."

According to the opinion by Judge Harry T. Edwards, White, 36, was first committed to the hospital in early 1968.

A few months later while on leave, he attacked five police officers trying to arrest his father and killed one officer. White was found not guilty by reason of insanity and committed again to St. Elizabeths.

Under this order, which is still in effect, he must remain at the hospital until a federal judge finds that he no longer is dangerous to himself or others.

Even so, Edwards continued, White assaulted a cabdriver while on unauthorized leave in 1971 and attacked several police officers while off the hospital grounds in 1978.

After the 1978 assault, Edwards wrote, White's ground privileges were suspended for just three weeks.

Within a year he was allowed to remain on the grounds unaccompanied for 12 hours a day -- from 9 a.m. to 9 p.m. -- although he was required to report at certain times for meals, work, and therapy.

White met his wife while she was a patient at St. Elizabeths, Edwards continued. After she was discharged, he married her at a church off the hospital grounds on March 10, 1979, although hospital officials did not become aware of the marriage until several months later.

Edwards said both White and his wife acknowledged later that he left the hospital grounds "on a routine basis" to visit her Anacostia apartment in the afternoon.

Edwards said that White stabbed his wife with a scissors on Dec. 7, 1979. She was treated at Washington Hospital Center and recovered.