They use racism, fear of racism to control and divert the various discussions. Just look at how the establishment uses it to attack Ron Paul and the liberty movement. If they scream racism they don't have to discuss tyranny. The accusation and witch hunt of racism is really no different compared to the fear McCarthy spewed in the 50s. Simply being called a racist is enough. No proof is required.
"When the people fear their government, there is tyranny; when the government fears the people, there is liberty."