What is the message received by Black people when such an event occurs?

How common is the experience described by Paul Butler of being stopped by the police (merely because he was walking down the street)?What is the message received by Black people when such an event occurs?What are the possible psychological and emotional effects of this type of experience?What is the best way, if any, to mentally overcome an event like this?What, if anything can/should be done in order to prevent such events from occuring?