President Trump can perhaps be forgiven for not understanding the quirks of federal District Court jurisdiction. Saturday he Tweeted, “Why aren't the lawyers looking at and using the Federal Court decision in Boston, which is at conflict with ridiculous lift ban decision?”

The elementary reason is this: one judge—Judge Nathaniel Gorton of the District Court for the District of Massachusetts––refused to enter an injunction. His order doesn’t have any legal effect. It did not even resolve the claims of the six plaintiffs in front of it, simply said that they were not entitled to an emergency order halting Trump’s travel-ban order before a trial.

The other, “so-called Judge” James L. Robart of the Western District of Washington, did issue an order—a nationwide “temporary restraining order” (TRO) that instructs Trump and the Departments of State and Homeland Security to stop immediately enforcing the travel-ban order.

While that order is in effect, it doesn’t matter whether another judge disagrees; the parties, from Trump on down, are bound. A “temporary restraining order”—which usually runs for a matter of days only––is an emergency measure designed to freeze the situation until the district court can hear arguments and full briefs from the parties. (In Washington v. Trump, that hearing is scheduled for Monday.) At that hearing, the plaintiff (in this situation Washington and Minnesota) will make their legal arguments and ask the judge for a “preliminary injunction,” an order that will freeze the situation until a full trial on the merits can be held. The government will argue that the law is on its side.

The order applies across the entire country, Judge Robart wrote, because a patchwork order—in which Customs and Border Protection enforced the order at some airports but not others “would undermine the constitutional imperative of ‘a uniform Rule of Naturalization.’”’ The quotes are from a 2015 opinion by Fifth Circuit Judge Jerry Smith, ruling on then-President Obama’s “deferred action” program for some undocumented immigrants. Conservatives adored that ruling; they are less enthusiastic about this one. But sauce for the nativist goose, Judge Robart implies, must be sauce for the immigrant gander. The same logic goes for his decision to find that the states of Washington and Minnesota have “standing to sue.” The states claim that they are injured by the order because it injures their people and in-state corporations by separating families and preventing the entrance of skilled workers. “State standing” was pioneered by Texas in its challenge to Obama; that chicken may not be all the way home to roost yet, but it is flapping homeward.

Monday’s preliminary hearing will address scope and standing again. Then the argument will turn to the merits—that is, is the executive order warranted by the immigration laws, and if so, is it constitutional?

The administration really might draw some comfort from the Massachusetts opinion. Judge Robart in Washington thinks the order violates the statute and the Constitution; Judge Gorton in Massachusetts thinks it doesn’t. Both are smart judges confronting a new issue.

We don’t and can’t know how the case will come out. Both sides have strong arguments.

First, the statutory issue. It arises because of possible conflict between two provisions of the Immigration and Nationality Act. The first, 8 U.S.C. § 1182(f) was adopted in 1952. It provides that the president may find “that the entry of any aliens or of any class of aliens into the United States would be detrimental to the interests of the United States,” and “suspend the entry” of those aliens. The second, § 1152(1)(A), was added in 1965. It provides that “no person shall receive any preference or priority or be discriminated against in the issuance of an immigrant visa because of the person's race, sex, nationality, place of birth, or place of residence.”

Combining these two suggests that the President can choose “classes” to exclude—as long as the “classes” aren’t based on “race, sex, nationality, place of birth, or place of residence”—which the travel ban order definitely is. That’s especially convincing since the anti-discrimination language was added after the “classes” language. But a court could say that the “any class” language limits the anti-discrimination language, instead of vice-versa.

The statutory language doesn’t ban discrimination based on religion, though. That’s a command drawn from the Equal Protection principle of the Fifth Amendment, as well as the Free Exercise and Establishment Clauses of the First Amendment. So does the “travel ban” discriminate against Muslims? Here again, the government says no: it is, they say, a total ban on refugee admissions, coupled with a geographic ban on visa applicants from seven Middle East nations––Iraq, Iran, Syria, Yemen, Sudan, Libya and Somalia. No religious discrimination there, right? (Especially, the argument goes, since there are plenty of predominantly Muslim nations not covered by the visa ban.)

There’s a potential fly in that ointment, however: the ban by its own terms exempts on a “case by case basis” from both the refugee and visa bans applicants from any country—including the disfavored seven—for a number of reasons, “including when the person is a religious minority in his country of nationality facing religious persecution.”

So: here’s an analogy that might convince a court. Suppose for some reason the government throws a travel ban around the following American cities—Detroit, Michigan; Jackson, Mississippi; Miami Gardens, Florida; Birmingham, Alabama; and Baltimore, Maryland. An alert demographer will note that these are majority-black cities. Further, imagine that the government includes a “case-by-case” exemption if “the individual is a member of a race that is in a minority in that city”—in other words, white. Could you keep a straight face at a claim that this was “race-neutral”? Note that lots of black people aren’t covered by the order—but that in the affected cities, the government is clearly—but its own admission--leaning against black people.

It’s not a precise analogy, and Judge Gorton wouldn’t agree with my example, since, he notes, the language “could be invoked to give preferred refugee status to a Muslim individual in a country that is predominately Christian.” My reaction to that is the sarcastic Briticism, and then you wake up—especially since Trump himself explicitly said the intent is to prioritize Christians. But a court has the option of ignoring presidential statements and simply following the text; and Gorton finds the exception neutral.

Assuming that the order does discriminate by religion, how serious a violation of Equal Protection would that be? Remarkably enough, that is still an open question before the courts. Most religion cases are tried under the First Amendment. But the First Amendment prevents discrimination against religions—thus it is mostly concerned with religious institutions and practices. Equal Protection would bar discrimination against individuals because of their religion in any aspect of life, not simply their religious activities. (“No Muslim prayers in this space” is First Amendment discrimination; “Muslim kids can’t play on the jungle gym” is Equal Protection discrimination.)

The Supreme Court has never addressed the second kind of religious discrimination. The best guidance on how a court would assess it comes from a recent case called Hassan v. New York Police Department, in which the Third Circuit struck down a NYPD program that surveilled Muslims all over the northeast; under Equal Protection, the court said, discrimination by religion was precisely as bad—and thus as presumptively unconstitutional—as discrimination by race.

But even if the order is found to be intentionally discriminatory against Muslims, the plaintiffs will still have a hurdle to clear: some cases, and some scholars, have argued over the years that equal protection simply does not apply to immigration decisions. In other words, they say, Congress—or a president given the power to do so by Congress—could decide to exclude all members of any race, nationality, or religion, without offending the Constitution.

Judge Gorton in essence bought that rationale. Because immigration decisions involve a “fundamental sovereign attribute” of the nation, he wrote (quoting earlier cases), they are “largely immune from judicial control.” Thus, he concluded, excluding immigrants by religion might make sense, and thus is likely permitted.

All told, the issues in the travel ban case are complicated and uncertain. The eventual decision could go either way—especially when it reaches the Supreme Court, as it likely will. That Court has shown some willingness to second-guess the federal government on the exclusion of aliens—but some hesitation as well.

So it’s hard to predict how it will come out—especially since there may very well be a ninth justice on the Court by the time it gets there.

The plaintiffs, however, have a secret weapon. Its name is Donald Trump and its venue is Twitter. Vulgar as it was, his tweet calling Robart a “so-called judge” and his ruling “ridiculous” must have delighted the lawyers for Washington and Minnesota.

Insulting judges and courts, I tell my students, is usually not considered brilliant legal strategy.