I'm reading The Gulag Archipelago now -- I'm around 530 pages in, so I just read the part about the common criminals beating up and robbing the political prisoners. It undoubtedly helped the thieves a lot that the political prisoners wouldn't stand up for each other, but if for some reason one did stand up to a criminal, his friends would take revenge later. The criminals were effectively united; the political prisoners could not have been more divided.

It's a heavy book, both in weight (1800 pages) and ideas, but everyone should read it.