Earlier today, a closely divided Supreme Court upheld President Donald Trump's policy barring most entry into the United States by citizens of five Muslim-majority nations. Chief Justice John Roberts' opinion for the Court took note of Trump's numerous statements advocating a "Muslim ban," and recognized that they are relevant evidence. In virtually any other circumstance, a policy with such a clear discriminatory motivation would be struck down as a violation of the First Amendment, which, among other things, forbids government policies that discriminate on the basis of religion. But the majority refused to do so because they concluded that presidential decisions on immigration policy are subject to only very minimal "rational basis" review. For reasons I summarized here and in an amicus brief I coauthored on behalf of several constitutional law scholars, there is no good justification for exempting immigration policy from normal standards of judicial review. This is especially true in a situation where evidence strongly indicates that the official national security rationales for the policy are just pretexts for the real purpose: carrying out Trump's bigoted "Muslim ban" promise. Whatever deference might normally be due to executive national security expertise surely does not apply in a situation where national security is not the true motive behind the challenged policy.
Sadly, the ultradeferential approach adopted by the majority can just as easily rationalize virtually any discriminatory exclusion of immigrants or refugees. The executive need only structure the policy in a way that targets a characteristic closely correlated with the forbidden classification (in this case, residence in a Muslim-majority nation), and concoct some sort of legitimate-seeming justification for the policy, perhaps supported by a cursory "review" whose supposed recommendations need not even be consistently applied.
Today's decision does have two notable bright sports. The majority does not reject the relevance of Trump's statements on the basis that they occurred during a campaign. Indeed, Roberts notes that this "extrinsic evidence" can be weighed. This implicitly rejects numerous claims that campaign statements cannot be considered as evidence of unconstitutional discriminatory motive, and prevents today's decision from creating a generalized road map for discriminatory policies, under which officials broadcast their true purposes during a campaign, and then speak more carefully afterwards. Unfortunately, the decision does create a very similar road map for discriminatory immigration policies.
The second bright spot is the belated overruling of Korematsu v. United States (1944), the notorious decision in which the Supreme Court upheld bigoted internment of some 100,000 Japanese Americans during World War II. Today's decision notes that "Korematsu was gravely wrong the day it was decided, has been overruled in the court of history,and—to be clear— 'has no place in law under the Constitution.'" That is a welcome statement. But the majority's statement that "Korematsu has nothing to do with this case" is much harder to credit. Both rulings involved closing judicial eyes to the true purposes of a discriminatory policy largely on the basis of special deference to supposed executive expertise on national security. Such excessive deference is no more justified today than during World War II.
I will have more to say about the Court's badly flawed travel ban decision later today and tomorrow, including in publications elsewhere that I will link to at the Volokh Conspiracy, as soon as possible.
UPDATE: It is perhaps worth noting that I have previously discussed the administration's argument (endorsed today by Roberts) that the travel ban is not discriminatory because it doesn't cover all the Muslims in the world, here and here.
UPDATE #2: I should note that the majority's reasoning leaves open the possibility that campaign statements (and other "extrinsic" evidence of motive) might be excluded in future immigration cases. Roberts says that "[f]or our purposes today, we assume that we may look behind the face of the Proclamation to the extent of applying rational basis review." But the possible constraints on looking "behind the face" he cites are all specific to immigration policy, and do not apply elsewhere. And once Roberts did choose to "look behind the face," he did not distinguish campaign statements from other evidence of discriminatory motive.