The lawsuit filed Wednesday in Multnomah County accuses the hospital of neglect.
The Oregonian reports the nurse accused in the incident last February, 38-year-old Jeffrey N. McAllister, was charged with sexual abuse and has pleaded not guilty. He remains in custody on an indictment that also alleges he sexually abused three other women in the emergency room.
Legacy Emanuel spokesman Brian Terrett says the hospital condemns any inappropriate conduct by employees and will investigate.
The state Nursing Board wants to revoke McAllister's license for reports of six inappropriate encounters with patients.
In a written statement to the board McAllister denied acting inappropriately toward any patient.