Officials at the University of Colorado know about a pattern of alleged date-rape drug use at a fraternity in Boulder, but say the law prevents them from naming the fraternity to police.

An investigation of sexual assault on college campuses found CU and others colleges across Colorado are withholding information about sexual assaults against students.

But the issue is more nuanced than first glance might suggest: Advocates say the secrecy is necessary to protect rape victims who wouldn’t come forward otherwise. Law enforcement officials say the secrecy may be allowing more people to fall victim.