As part of any mature civilization is a court and justice system created in order to promote order and to assure the public safety. While there are many ingredients to such a system, one of the necessary ingredients, is having under State Control, a designated arm of the government that makes sure to impose order when it needs imposing, and to bring miscreants to justice. That arm of justice is presently known as the police, to which the police worked in conjunction with civil authorities to maintain and support civil society with the police force aiding in the enforcement of particular codes and laws of such a jurisdiction.
In a nation such as America, the police are not a force unto themselves, although in truly exceptional cases they can conceivably be, as they are instead the enforcement arm of the State. This means that police, are not independent agents of the State, but are first responders to the State and its laws, and in particular the peculiar enforcing of such laws within that jurisdiction.
While a police force has many purposes, there are two basic and fundamental purposes that any police force has: to which the first is not so much to see that the law is obeyed and upheld within a particular city, but instead to see that the law, as arbitrated by those in authority, is obeyed and upheld in that city. This means that there is conscious recognition by policing authorities that they are not in themselves to go about their business in such a manner so as to disturb those that are the masters and payers-in of said system, with their secondary purpose being specifically to setup policing so as to keep the barbarians at the gate. But who are the barbarians?
The barbarians are always define by the State, and therefore the State decides which party is on the inside and is privileged and which parties are on the outside, and should be suppressed. That is why in virtually any civil disturbance within a given city, the police force is almost always on the side of those that control the city politics of that city, and thereby the police force as a whole pays little or no attention to the law or even their purported purpose, such as "to serve and protect", but instead makes sure to obey those that are truly in authority.
This means, for the uninitiated, that believe that in those inevitable situations which bring forth justifiable civil disputes, to which it would appear that each side has its merits, and thereby that the purpose of the police in such a situation should be to see that each side is protected equally and in such a manner so as to reduce bloodshed and unnecessary drama, that this viewpoint is nakedly naïve. In point of fact, in most cases, one side will be strongly supported by the State, to the exclusion of the other, which should make it vividly clear as to whom or whom not the barbarians are, and once identified as barbarians, expect those barbarians to be stopped at the gate and driven far, far away.