Protestors would be a system for punishing inhuman prisons. They would come in groups (varying based on prison size, rating of crimes, etc) that would be the stereotypical protesting mob. They would carry signs (possibly, if the developers choose to code it in, corresponding to crimes committed. But that would be hard). They would respect fence boundaries (unless they start rioting). They can be handled by police (if they become violent (or if they don't, but that makes your inhumanity value worse)), armed guards (starting riots occasionally) and fixing your prison. Protestors only stick around for a few hours normally, but will set up tents and stick around in extreme cases.
Inhumanity is rated based on various factors, such as use of solitary confinement (classified as torture under international regulation), use of execution (especially when the reduced liability upgrade is purchased) (because people don't like that, apparently), small cells, low meal quality (has reduced impact, because people don't particularly care about that), lack of visitors (weighs more as time goes on, so as not to punish you on more prisons) (these protestors would have family member names), and anything else that one might consider inhumane.
Also, based on something that I read in another thread, inhumanity would have political pressures. Politicians could make laws and regulations that would prohibit certain things. Political pressures could also affect grants, reducing money from them or even locking them down until you improve your prison. To prevent this, you could hire a lobbyist (via the lawyer or something).
Sorry for the bad writing. I suck at this
