“It’s a lot easier to act presidential than to do what I do,” President Trump told a Tampa audience this summer. He’s wrong, and it may have real-world implications if he invokes federal “emergency” statutes to unilaterally build a Mexican border wall.

His “acting presidential” bit is running gag that dates back to his campaign: joking that he, too, can “act presidential,” President Trump stiffly imitates a dull monotone address, sometimes breaking a presidential-sounding speech into component parts (“And then you go, ‘God bless you, and God bless the United States of America’”), before telling the audience, “that’s much easier than doing what I have to do . . . but this”—the full Donald Trump experience—“is much more effective.”

Perhaps it is effective in rallying his political base, but it has not been a particularly effective approach to governance. And we may see firsthand the costs of eschewing presidential norms if the Trump attempts to build a Mexican border wall by invoking federal “emergency” laws.

As the entire political world now knows, federal laws are replete with provisions affording the president special powers upon his declaration of a state of “national emergency.” But, as David French detailed in a pair of posts at National Review, none of the available emergency-power statutes would actually justify President Trump’s construction of a Mexican border wall.

The president’s advocates have invoked emergency-power statutes that empower the President to redirect funds in order to unilaterally “construct . . . civil defense projects that are essential to the national defense” (33 U.S.C. § 2293); or to “undertake military construction projects . . . not otherwise authorized by law that are necessary to support such use of the armed forces” (10 U.S.C. § 2808).

But their arguments all suffer from a simple but fundamental flaw: they are unsupported by the facts. The Mexican border wall is not “necessary to support” current use of armed forces—indeed, the president has not even suggested otherwise. Nor is the Mexican border wall “essential” to “the national defense” in any reasonable sense of those terms.

And, above all else, there is no reasonable basis on which Trump can show, under the triggering statute (50 U.S.C. § 1602), that we actually are in a period of a “national emergency.” Indeed, the president’s own handling of the border wall issue over the last two years proves otherwise—especially when he rejected a proposal to fund the wall because it was paired with a plan to give 1.8 million immigrant children amnesty and a path to citizenship.

The president’s proponents are untroubled by this gap between the law and the facts, in large part because they do not believe the Supreme Court would actually require the Trump administration to prove its case. Rather, they expect the courts to defer to President Trump’s statement that we are in a national emergency and that the wall is (per the statutory provisions) either “essential to the national defense” or “necessary to support such use of the armed forces.”

“Courts generally have deferred to the judgments of presidents on the basis for such national emergencies,” writes Jonathan Turley in The Hill, “and dozens of such declarations have been made without serious judicial review.” At AmGreatness.com, John Eastman agrees: “it is extremely unlikely the Supreme Court would second guess the commander-in-chief” on questions of military need. At ConservativeReview.com, Daniel Horowitz punts the question of whether the current situation actually “rises to the level of an emergency or not,” because that question “is the subject of a political debate that should be settled between the political branches, not the courts.”

In short, they are counting upon the courts, or at least the Supreme Court, to give president Trump the deference that courts conventionally afford to presidents on questions of emergency power—despite the fact that, now two years into his presidency, Donald Trump has largely defined himself as a departure from presidential norms and traditions.

There is good reason to doubt that the justices will be so deferential to the Trump administration’s invocation of emergency powers. The court’s traditional deference to presidents in emergencies reflects, among other things, a judicial recognition that presidents often act on the basis of confidential facts and with the benefit of executive branch expertise. Here, by contrast, the facts of the situation are in plain view. And equally self-evident is President Trump’s actual motivation for building the wall: not sudden emergency circumstances, but his campaign pledge to build the wall, now thwarted by Republicans’ loss of the House of Representatives.

Perhaps the administration is emboldened in this case by the Supreme Court’s recent decision in Trump v. Hawaii—better known as the “travel ban” case—because the five-justice majority deferred to the president’s judgment of necessity and declined to impute indications of Trump’s ill motives into the facially sufficient presidential decision. But that case is much different from the present one.

In the travel ban case, the court stressed that the president ordered his agencies to “to conduct a comprehensive evaluation” of the risks posed by entry of foreigners into the United States; then, based on that extensive review, the president issued a proclamation “setting forth extensive findings” as to facts ascertained by the agencies; and finally, the president’s Proclamation fixed country-specific limitations that reflected the administration’s comprehensive research.

In the border wall fight, by contrast, the president’s factual claims are far removed from the actual evidence, and the powers that he asserts are blunt and immense. For that reason, the president should pause before assuming that the five-justice majority will be as deferential in a challenge to his “emergency” border wall.

And if the justices have doubts about a declaration of emergency by President Trump, then their doubts will only be redoubled by the sheer magnitude of power claimed by the president. Not only does he claim the power to build a bridge or similar piece of military infrastructure, but rather a massive wall for hundreds of miles, radically changing the nature of our border, at the cost of billions of dollars, and with serious impacts on private landowners and on the environment. And all of it in the face of Congress’s refusal or failure to specifically authorize and fund the project.

In that respect, an attempt by the Trump administration to build a border wall unilaterally may call to mind some of the Obama Administration’s own aggressive and unprecedented assertions of immense power, like the EPA’s greenhouse gas regulations or the FCC’s net neutrality regulations. When the Supreme Court struck down one iteration of the EPA’s greenhouse gas regulations in 2014, Justice Scalia’s opinion stressed that the Administration’s interpretation of the law strained credulity because “it would bring about an enormous and transformative expansion” of the Administration’s power “without clear congressional authorization.”

Scalia added, “[w]hen an agency claims to discover in a long-extant statute an unheralded power to regulate ‘a significant portion of the American economy’ . . . we typically greet its announcement with a measure of skepticism.” So, too, might a majority of Supreme Court justices today if the Trump Administration suddenly discovers in old statutes the power to unilaterally build the border wall that Congress disfavors.

This may all come as a surprise to President Trump, who seems to think that his border wall fits comfortably within the limits of the emergency statutes. He said as much in his Rio Grande press briefing on Friday: “Don’t forget, national emergency is going through Congress because that already went through Congress.” (Or, translated into English: “To act pursuant to a national-emergency statute is to act pursuant to Congress, because the statute was enacted by Congress.”) And, he added, “[t]hat’s what it’s there for.”

But that is not actually what the emergency statutes are “there for.” Congress vested presidents with great power to act in the case of genuine emergencies—not just when a president, in a political bind, simply says “national emergency,” as if they are magic words that make the Constitution’s requirements for lawmaking and money-spending suddenly disappear. It is the difference between a president’s cynical assertion of power and a president’s faithful execution of the law.

For two years, Donald Trump has done everything he can to define himself as an unconventional president. It may come at the cost of the deference that justices conventionally afford to presidents.