Violence is justified against those who initiate the use of physical force. Initiated violence is an issue of not defining a clear code of rational morals. Racial violence is present in places with irrational cultural (whim worshipping) proclivities. Self-respecting human beings recognize and respect other human beings on the trader principle. The trader principle was a cultural force prior to the Sherman Anti-Trust, New Deal, etc.
Sounds like the Obama administration.