Marriott Hotels, which was sued last year for allegedly turning a blind eye to sex trafficking at three of its Philadelphia hotels, can bring third-party defendants into the litigation, a federal judge has ruled, addressing open questions about how liability can be apportioned in the burgeoning area of sex trafficking litigation.

U.S. District Judge Mark Kearney of the Eastern District of Pennsylvania granted Marriott International’s motion to file a third-party complaint against the franchisees who ran the hotels where the trafficking took place and those who directly trafficked the plaintiff.