Guards can rape prisoners, though it's generally frowned upon.  Generally, guards must remind prisoners that inmates shouldn't question the authority of the guards, under any circumstances.  That's why Alicia was tortured in front of the population, because she gave a prisoner a blowjob.  She had to get on her knees to do it.  That's a show of submissiveness to an inmate.  If a guard makes YOU get on YOUR knees, then you're the submissive one.  Got it?