Why have Civil Authority?

"One fierce opponent of civil rights legislation, William F. Buckley Jr., admitted... “I once believed we could evolve our way up from Jim Crow,” Mr. Buckley said in 2004. “I was wrong: federal intervention was necessary.” quote from "Rand Paul and the Perils of Textbook Libertarianism," New York Times, May 21

The extent of the right wing Christian posturing against the government leaves me a little chagrinned. Civil authority was developed in part to stop evil doers and to protect weak. Jesus said he came, among other things, to free the oppressed.