i think that abuse is inherent in a situation of police power, and that you're not going to get away with thinking the problem is 'a few bad apples' while of course the vast majority of police officers are doing a bang-up job, as it were. i actually don't think 're-training' and so on is going to address the basic issue at all.
so you are arming one part of the population against the rest, or authorizing some to use violence and coercion that, for the others, would be criminal. the first thing to ask is what sort of person, overall, is likely to want to perform this role, and why. i am sure there are various motivations. one is surely an attraction not to the law or to the public but to the power, which is of the most concrete variety: real control of real specific people. and then you should contemplate the effect of routinely having this sort of power over a decade or whatever it may be. a certain air of arbitrary superiority is likely to develop, due to the real superiority.
the legal status of a police officer can be accurately reprersented as a series of legal impunities, as being authorized to do what would be crimes for others: binding or kidnapping people, for example, strutting around with guns and clubs on their hips, and so on. and it relies also on an informal exemption that is much more wide-ranging than that, as seen in the cases before us. these things are not addressable, i think, within the basic conceptuality that presupposes that such power is necessary and legitimate.
i do not think it is particularly plausible that constituting this sort of power is likely to reduce violence in the society as a whole. or, i wonder what evidence could actually be produced that it does? this is always asserted at the outset; it is 'common sense'. but the idea of arming one group against the others and immunizing them from the law does not, let's say, obviously entail a reduction in violence or crime however construed. and notice that in various complex ways this police power will of course mirror the power hierarchies of the society: racial, for example, and then it reinforces or reproduces or enforces those hierarchies. if you really thought about the role of policing in racial oppression through our whole history, you'd see that it is central: a necessary condition of the whole horrendously violent history, and ever more so in a situation in which mass incarceration replaced jim crow as a mode of segregation.