To understand why I think disciplinary originalism is valuable, let’s take a look at one of the most widely condemned of SCOTUS decisions, Korematsu vs. the United States. In Korematsu the court allowed the practice of evicting United States citizens, often native-born citizens, from their homes and moving them away from the West Coast simply because they were of Japanese descent. The vote was 6-3, and each of the justices who voted in favor of the executive order that mandated the evictions  was appointed by President Roosevelt, the man who issued that order. (In a separate but closely related case, the Court ruled that such citizens could not be “detained,” thus depriving the internment camps for Japanese-Americans of legal sanction.)

The chief interest of Korematsu, for today’s reader of the history, is the dissent by Justice Robert Jackson, later to become the Chief Prosecutor at the Nuremberg Trials. In the first stage of his dissent — which you may see in full by going here and scrolling about three-fourths of the way down — Jackson points out that Fred Korematsu was a natural-born citizen of the United States whose loyalty to his country had never been questioned by anyone. He was merely living and working in the place of his birth, but was by the Executive Order obliged to turn himself in to military authorities — an obligation that he would not have faced had he been even “a German alien enemy, an Italian alien enemy, [or] a citizen of American-born ancestors, convicted of treason but out on parole.” Yet he was different from those others “only in that he was born of different racial stock.” Jackson continues:

Now, if any fundamental assumption underlies our system, it is that guilt is personal and not inheritable. Even if all of one’s antecedents had been convicted of treason, the Constitution forbids its penalties to be visited upon him, for it provides that ‘no Attainder of Treason shall work Corruption of Blood, or Forfeiture except during the Life of the Person attained.’ Article 3, 3, cl. 2. But here is an attempt to make an otherwise innocent act a crime merely because this prisoner is the son of parents as to whom he had no choice, and belongs to a race from which there is no way to resign.

This point would have been sufficient in itself to declare Roosevelt’s order unconstitutional, but Jackson discerned a larger and greater issue at stake:

Much is said of the danger to liberty from the Army program for deporting and detaining these citizens of Japanese extraction. But a judicial construction of the due process clause that will sustain this order is a far more [323 U.S. 214, 246] subtle blow to liberty than the promulgation of the order itself. A military order, however unconstitutional, is not apt to last longer than the military emergency. Even during that period a succeeding commander may revoke it all. But once a judicial opinion rationalizes such an order to show that it conforms to the Constitution, or rather rationalizes the Constitution to show that the Constitution sanctions such an order, the Court for all time has validated the principle of racial discrimination in criminal procedure and of transplanting American citizens.

Jackson’s point here is exceptionally acute: this is not a matter of “rationalizing” — giving an implausible intellectual account of — the order, but rationalizing the Constitution. Which is a far more dangerous move.

The principle then lies about like a loaded weapon ready for the hand of any authority that can bring forward a plausible claim of an urgent need. Every repetition imbeds that principle more deeply in our law and thinking and expands it to new purposes. All who observe the work of courts are familiar with what Judge Cardozo described as ‘the tendency of a principle to expand itself to the limit of its logic.’ A military commander may overstep the bounds of constitutionality, and it is an incident. But if we review and approve, that passing incident becomes the doctrine of the Constitution. There it has a generative power of its own, and all that it creates will be in its own image. Nothing better illustrates this danger than does the Court’s opinion in this case.

People are often automatically dismissive of “slippery-slope” arguments, as though no slopes are ever slippery; but once a metaphor is dead it’s dead. Justice Cardozo’s phrasing may be more useful: “the tendency of a principle to expand itself to the limits of its logic.” This tendency is almost inevitable in SCOTUS decisions, because of the power of precedent: only rarely is a decision walked back; rather, a “passing incident” very easily and naturally “becomes the doctrine of the Constitution” when justices see different situations in which it can be applied. All the pressure is on one side, towards expansion rather than contraction of the principle.

Such expansion of a principle is all the more likely to happen when popular opinion, especially elite popular opinion, is also strongly on one side. FDR’s decision to move Japanese-Americans from their homes was quite popular (as were the internment camps) and eight of the Justices had the further pressure of owing their positions on the Court to the Roosevelt. What they needed — but what only three of them had — was a jurisprudential principle substantial enough to make a counterweight to those pressures. All three of the dissenting judges had that principle, but it was most fully developed in and articulated by Jackson.

Just a few months ago Justice Antonin Scalia was asked, by law students at Santa Clara University, which Supreme Court opinion he most admired. He named Jackson’s dissent in Korematsu.