on the Black Panther party in the 1960s are a good place to start with a history of modern racist policing in Chicago. The Panthers launched school breakfast programs and medical clinics; they also stocked firearms and insisted they would resist police brutality. The police and their advocates were incensed;The FBI infiltrated the Panthers and provided police with a diagram of the apartment of one of their most important young leaders, 21-year-old Fred Hampton.
Part of the problem is police immunity. You can't sue a cop no matter what they have done In Colorado they signed a bill doing away with police immunity.
You obviously seem to have missed out on there being a mass shooting in Chicago last night. Presumably you think that police should not have tackled that either.
If you're surprised that an American teenager was punched in the face while in Chicago then you haven't visited the American city, Chicago. They have a 'knockout game' that rock your socks.
bet the teenager deserved it