I am extremely appreciative of this excellent article. It is thoroughly researched and puts the issues out there so clearly. I worked as a prison psychologist for ten years, probably one of the best run in the U.S. (Airway Heights Corrections Center), and still we had problems with sadistic officers. The issues that make it impossible to dismiss them (the union being a primary factor) were well highlighted in the article. However, the Superintendent (aka Warden) is ultimately responsible, and the chief of correctional officers (aka Lieutenant) also carries much responsibility. Although their hands are often tied by the union, they are responsible for the prison culture.
The lack of cameras was unforgivable and that being allowed to continue places responsibility squarely on the Superintendent.
In my prison, any use of force had to be videotaped. Period. Hence our sadistic officers could not step into violence.