Lawyers for Paula Johnson, the mother of one of two babies switched at birth at the University of Virginia Hospital, have filed suit against the Los Angeles-based manufacturer of the identification bands worn by both mothers and their babies just after birth.

Johnson's attorneys say Precision Dynamics Corp. is partly to blame for the much-publicized baby switch because its plastic identification bands could easily slip off.

Investigations by the Virginia State Police and the Virginia Department of Health have not identified a precise cause for the switch, but both probes found problems related to the bands on the two baby girls.

Johnson last month filed a $31 million lawsuit against the University of Virginia Medical Center, alleging that doctors and nurses there improperly put the bands back on the babies. But lawyer John T. Blakely said the company was partly to blame for the switch four years ago.

"They share responsibility for what happened at the U-Va. Medical Center," Blakely said. "The initial design defect set the tragedy in motion. Then the personnel at the medical center had several different opportunities to prevent the tragedy and negligently failed to do so."

A spokesman for the company called the lawsuit "totally groundless" and accused Johnson's lawyers of trying to find a defendant with a lot of money to sue.

In a statement, the company's president placed the blame for the switch on the hospital staff and said the tragedy would have been avoided if the doctors and nurses had followed the company's instructions.

"Every box of maternity identification band sets that we manufacture comes with a product-use information card instructing hospital staff that the bracelet should fit snugly," said President Walter W. Mosher Jr.

The lawsuit, filed yesterday in California Superior Court in Los Angeles, seeks unspecified damages.

Blakely said he would argue that Precision Dynamics Corp. knew its product was poorly designed and did not work properly. The company now markets bracelets under the product name "Snug Fit," an indication, he said, that its earlier bands did not fit that way.

"The way the product is designed, it can't be applied the way they suggest," he said.

CAPTION: Paula Johnson says Precision Dynamics shares the blame for the baby switch.