Law & Order SVU S9E17 "Authority"
A telephone voice impersonating a police officer asks people to do morally questionable and illegal things. SVU detectives learn that this plan was orchestrated by an engineer Merritt Rook (Robin Williams) in order to convince the public to be more discerning and oppose authority. Rook turns his trial into a media circus and seizes an opportunity to abduct Olivia Benson. With the help of Rook's co-worker (Ka-Ling Cheung), Elliot is able to learn about the man's tragic past and track him down. In an apparent hostage situation, Rook tries to make Elliot inflict pain on her by way of a Milgram experiment.