15-9. Several years ago, 8,000 Amtrak workers agreed not to disrupt service by walking out, at least not until a court hearing was held. Amtrak had asked the courts for a temporary restraining order, and the Transport Workers Union of America was actually pleased to postpone its walkout. The workers were apparently not upset at Amtrak, but at Congress for failing to provide enough funding for Amtrak. What, if anything, can an employer do when employees threaten to go on strike, not because of what the employer did, but what a third party—in this case, Congress—has done or not done? What laws would prevent the union from going on strike in this case?