The establishment most likely does not have liabilty. A person, business, etc. is not liable for criminal assaults which happen on its property or premises simply because there was an assault. That is, the establishment does not act as an insurer for its patrons or visitors, but is only liable if it was at fault in some way.Fault in a case like this generally requires special circumstances which do not commonly exist, such as the attack was by an employee of the establishment; the attack was by a patron or visitor who has caused problems before and whom the establishment should have been on guard against; the restroom has been the site of multiple assaults, which would then generally require the establishment take some greater precautions (e.g. an attendent).Without some special circumstances, there would almost certainly be no liabilty. You could, however, sue your attacker if you chose.