I'm usually a single book kinda guy, but I'm currently reading several books at once, including Jane Mayer's The Dark Side and Arsenal: The Making of a Modern Superclub. The book that I'm reading that is most relevant to work is Michael Lipsky's Street-Level Bureaucracy. I picked it up on the recommendation of Ron Corbett, who is the executive director of the Massachusetts Supreme Court. The writing is a little dry and the examples are dated (the book is more than a generation old), but I think the general message is still a valuable one.
Lipsky basically argues that while much of the public and media attention is drawn to policy debates at the highest level of government (e.g. what Congress does), the reality is that a great deal of policy is made at the ground-level by front-line government workers -- police, teachers, social workers, judges, benefit administrators etc. While many tend to think of these folks as simply implementing policies that are determined by those above them on the organizational hierarchy, the truth is that there are always gaps to exploit and numerous opportunities for discretion.
It probably goes without saying, but one of the implications is that if you want to change the behavior of any institution (say, the justice system), it is not enough to win over the commissioner, since many of the real decisions that affect people's lives the most are made not in the executive suite but by street-level bureaucrats.