From today's New York Times:
Police unions do have critics on the right. But thanks to a mix of cultural affinity, conservative support for law-and-order policies and police union support for Republican politicians, there hasn’t been a strong right-of-center constituency for taking on their privileges. Instead, many Republican governors have deliberately exempted police unions from collective-bargaining reforms — and one who didn’t, John Kasich of Ohio, saw those reforms defeated.
In an irony typical of politics, then, the right’s intellectual critique of public-sector unions is illustrated by the ease with which police unions have bridled and ridden actual right-wing politicians. Which in turn has left those unions in a politically enviable position, insulated from any real pressure to reform.
Yet reform is what they need. There are many similarities between police officers and teachers: Both belong to professions filled with heroic and dedicated public servants, and both enjoy deep reservoirs of public sympathy as a result. But in both professions, unions have consistently exploited that sympathy to protect failed policies and incompetent personnel.