The first point: not only are police forces around the country supplied with military weapons and equipment for little or no good reason but police officers are more likely than not to have been recently deployed to war zones, probably without the benefit of any real process to re-enter civilian life.
The second point: most police officers get all of their training in psychological and unarmed compliance techniques in the academy without benefit of further training or retraining as new techniques are developed. Since they don't know how to induce compliance with their voices or by using minimal force with their hands (joint locks and such), they are more likely to resort to choke holds, beatings, nightsticks, tasers, and guns.
When the USA's Afghanistan and Iraq wars had just begun over a decade ago, I read about the disproportionately high numbers of first responders - police, fire, EMTs - who were members of the Reserves and National Guard and being deployed, multiple times, to war zones. I took to asking the police I saw in the course of my travels whether those deployments were having an effect on their work. The answer I always got was "No," but I never really believed it.
In some way, I think the whole country has an undiagnosed case of PTSD due to the Bush/Cheney wars. About time he began to admit it and began to do something about it. How many of the Ferguson, MO police department have been deployed in our recent wars? Did any of them get counseling after their service?
Less than a year ago, I attended a martial arts seminar with a retired NJ cop who taught unarmed compliance techniques. He used me as his crash test dummy and I can testify to the fact that what he did worked, whether it was a shout or purely physical. He was trying to start a business working with municipalities or individual police to train them in effective unarmed compliance techniques but found that there was no money and no time available. He told me that usually the only annual requirement for a police officer was to a visit to the gun range and a qualifying test with a firearm. After the police academy, there is usually no continuing training at all in unarmed compliance.
Most of the discussion I've seen about the seeming epidemic of bad policing and the continuing deaths of primarily African-American men for minor infractions or no good reason (including the cousin of my tai chi teacher recently, see http://www.salon.com/... ) concentrates on the equipment, the camouflage uniforms, the SWAT teams, the idea of police as an occupying force rather than peace officers. These are the outward signs and are easy to distinguish. My two points, my two cents focus on the inward changes that let this injustice fester and grow: our wars have come home and we don't train our civil servants so that they have the confidence and expertise not to use possibly lethal violence when they don't have to.