Despite their culture of violence, American police have a 3% prosecution rate for their brutality thanks to the collusion and protection of their unions, District Attorneys, and City Councils. Even our ethics commissions and IPR's are stacked & rigged. Please sign (and share) my petition demanding change, directed at the DOJ and IAPC. 
https://secure.avaaz.org/en/petition/Police_can_be_improved_Stop_screening_out_the_best_and_brightest_to_serve/?pv=7
p.s. If you don't believe me, check your state's Corruption Risk Grade Card and check its overall grade, then drill in and check your ethics grade.
http://www.publicintegrity.org/2015/11/09/18822/how-does-your-state-rank-integrity