Lately I've been hooked on watching these documentaries by Frederick Wiseman. The thing about these is they are almost entirely made up of dialog between the subjects. There are no interviews, no music, no one to explain what might be happening in the scene, and no one acknowledges the camera (He will not film if he thinks anyone is "acting"). They would probably be considered boring by a lot of people, and not a lot of what happens will even make you think about about it until afterward because it's so natural, but they really give an amazing look into our institutional systems if you're into that sort of thing.
Probably the most famous one is Titicut Follies, filmed at Bridgewater State Hospital, a hospital/prison in Massachusetts for the criminally insane. If you want to see One Flew Over The Cuckoos Nest without the cinematics, I suggest you give it a watch. There is some disturbing content (force feeding, abuse by staff, dehumanization) in it so be warned.
Others I've seen are High School, Juvenile Court, and I watched the first half of Public Housing last night, a look into the residents and those in charge of Ida B. Wells housing project in Chicago.
All of these are worth checking out if you're interested in this stuff. Despite some of them being old and out of date, they definitely give a good and interesting look into "the system".