What We Learned in Oklahoma City by Bill Clinton

We are again dealing with difficulties in a contentious, partisan time. We are more connected than ever before, more able to spread our ideas and beliefs, our anger and fears. As we exercise the right to advocate our views, and as we animate our supporters, we must all assume responsibility for our words and actions before they enter a vast echo chamber and reach those both serious and delirious, connected and unhinged.

Civic virtue can include harsh criticism, protest, even civil disobedience. But not violence or its advocacy. That is the bright line that protects our freedom. It has held for a long time, since President George Washington called out 13,000 troops in response to the Whiskey Rebellion.
http://www.nytimes.com/2010/04/19/opinion/19clinton.html?th&emc=th