The problem with your counterargument is that police brutality has been going on for years, despite the change of political administration throughout the decades. The fact is police brutality has not gone away, hence, how can one not make a characterization of the said institution.
Years? Have you ever read history? I seem to remember reading the Romans were particularly brutal -- in one particular case against an innocent person from Galilee. Again before that, killing every male child born to each family. That supposedly happened several times at key points in history. The English, French, Spanish, you name it. Every government has enforced its laws with sometimes the most vicious and unjust means and motives imaginable. This is not a recent US-created development.
This is a nation of over 325 million people. We have 50 states, 5 major territories, 3,007 counties, and 19,495 incorporated cities, towns and villages.
The federal government has it's own separate and unique law enforcement jurisdictions.
Are you trying to argue with that many people under so many local, state and federal jurisdictions, you expect there to be a "political administration" with the solution for corruption, "brutality", and every other bad action perpetrated by government, law enforcement, organized crime and so on at every level from top to bottom?
If you have the answers, please tell the rest of the country. I don't know why the hell you've been waiting so long to share it!
The phrase, "Power corrupts" has been proven time and again. How do you propose to take the human condition out of law enforcement without introducing complete anarchy?