What’s so bad about siding with the “prisoners”? Not with the “criminals” mind you, just the “prisoners”.
In many countries, prisons have the mandate to “reeducate and reinsert into society”, and while privation of liberty is a punishment in itself, it’s intended only as a way to turn criminals too dangerous to let loose, into upstanding citizens once they do their time.
Prisoners can be “citizens in the making”, not just “criminals thrown in a hole”. That might be the first point to try to get through.