I think this is a very good distillation of the many inputs that drive police corruption. However, I'm ultimately unpersuaded by the new oversight agency put forth in the conclusion to rein it in. This is in no small part that there were no substantive discussions of the power of police unions in protecting officers and the role they may play in establishing the new oversight mechanism or their influence in furthering the corrosive cultures that breed widespread corruption.
If given the opportunity, I would grade this book at 3.5 for researchers in police reform, but gave it 4 on the principle of rounding up.