Northwest Airlines has threatened to discipline or possibly discharge union employees who they learned were planning to picket in order to bring attention to safety and security issues. Union members are specifically protesting the company's practice of having overseas and third-party repair stations do maintenance on Northwest aircraft. The company alleges that the picketing would be very damaging to business and compromise airline operations.
See "Northwest Airlines Threatens Picketers", The New York Times, June 23, 2004