If the Supreme Court were to accept the plaintiffs' logic in Trump v. Hawaii, the judicial branch will gain new powers over defense policy.
While Presidents have different objectives, the constraints of the politics of a given era tend to make them converge on tactics. An example today is the presidential use of untested executive powers to satisfy their partisan bases. President Obama could not get Congress to agree to enact legislation that would permit immigrants who had been taken to this country as minors to remain as residents. He thus resorted to a claim of unilateral authority. Obama declined to deport a huge class of illegal immigrants and provided them with the right to work in the United States. Now President Trump cannot get Congress to fund his “beautiful” wall. Like Obama, he is contemplating unilateral action, in this case the use of national emergency power to allow him to build it.
My point is not to talk about the merits of either action—although I am skeptical of both—but to illustrate how such actions not only reflect our polarized times, but also create more political polarization. As the parties become polarized, the Presidents become more extreme on the political spectrum. Presidents tend to represent the median of their party, because party members have so much influence in the presidential primary process. But the median members of the House and Senate fall more in the middle of the spectrum, because those bodies contain some more conservative Democrats and liberal Republicans. Thus, Senators Susan Collins is more centrist than Trump, just as Senator Joe Manchin was more centrist than Obama.
The rules of the Senate also create ideological space between the President and Congress, even when party of the President controls both chambers. Passing legislation there generally requires sixty votes in the Senate. That supermajority rule likely makes the pivotal Senator a member of the minority party ideologically distant from the President.
As the result, the President will almost certainly fail to enact some of the legislation most important to the most ideological members of his party. When he controls both chambers, he may refrain from exercising unilateral powers, because it is hard for him to simply blame the other party. But when he loses control of one chamber, he can more easily play the blame game. And the failure to deliver over time makes his most extreme supporters impatient. And he needs the energetic support of these supporters if he is to be reelected or get the successor of his party elected.
But unilateral actions by the President then exacerbate the very partisanship that prompted them. Opposing partisans naturally believe that he is acting lawlessly and are then more likely to egg on partisan actions of their own side and unilateral actions by a President of their party. Moreover, those who disagree with the President’s action on the merits become more likely to become partisans themselves.
One possible legal mechanism to temper this partisan spiral is for courts to interpret claims of unilateral power very strictly. That is, unless it is clear that the Congress has given the President a unilateral power, he should not be able to exercise it. This kind of clear statement rule would have its roots in the non-delegation doctrine itself. Even if the Constitution leaves it as a legislative decision whether to delegate to the President what amounts to legislative power, the Court can nevertheless require Congress to make this decision unmistakable. That requirement at least puts more accountability for the decision on members of Congress. And importantly for our era, a clear statement rule would also limit the instances in which a president can unilaterally energize the cycle of polarization.