A rare find involving text communication between a police lieutenant and a local fascist group, Patriot Prayer, and published by a local Portland (OR) newspaper, Willamette Weekly, is an illustration of the functions of police to protect the ruling capitalist class. Whenever the ruling class is threatened they turn to violent groups to salvage their rule. The classic example of this is in the Great Depression of the 1930s when numerous workers' parties sprung up all over the West. Many US and other European capitalists supported and funded the Nazi Party in Germany. (See also my commentary here for an elaboration in history of this tendency.)
McNalley offers an excellent general observation that the Portland incident illustrates:
These events speak to the historically prevalent trend in the United States of police forces working hand-in-hand with the ultra-right. This is evident from the history of policing as an institution in this country, including their origins as slave catchers and union busters, the coordinated attacks on the Black liberation movement, and the continued over-policing of peaceful protests at Standing Rock and of the Black Lives Matter movement. The police do not exist to protect the people. The police exist to protect the interests of the ruling class and the capitalist system that keeps the majority of people marginalized and oppressed. To that end, they will continue to join forces with violent reactionary groups like PP [Patriot Prayer] who uphold the status quo through force and intimidation. Only by overturning the capitalist system can we hope to effectively and permanently end the threat posed to our communities by groups like PP and the police forces that enable and support them. [my emphasis and insertion]