How Antonin Scalia’s ghost can block Trump’s wall

US government cannot do things whose cost outweighs their benefits, the justice wrote, and the proposed barrier at the border with Mexico does exactly that

nited States President Donald Trump may stumble on an unexpected obstacle as he tries to build a wall along the Mexican border: Antonin Scalia. This may seem surprising, considering that Trump has called him a “great” justice. But in one of his last opinions, Scalia supplied a powerful weapon to resist Trump’s plans for a border wall. Scalia’s June 2015 opinion in Michigan vs Environmental Protection Agency may not seem helpful at first sight. It blocked an EPA rule that would have limited mercury emissions from power plants. The Clean Air Act instructs the EPA to issue “appropriate and necessary” regulations and Scalia said that language required the EPA to consider the costs of its proposed rules, which it did not properly do. “No regulation is ‘appropriate’ if it does significantly more harm than good”, Scalia wrote. And even though the final vote in the case was 5-4, all nine members of the court agreed that the EPA could not ignore the costs of its actions when deciding whether or how stringently to regulate.

Why is Scalia’s opinion an obstacle to Trump’s wall-building plans? Trump is reported to be planning to rely on a law called the Secure Fence Act of 2006 as a source of statutory authority for the wall — apparently to avoid asking Congress to pass a new statute, which could be filibustered by Senate Democrats. But the 2006 law authorises the secretary of homeland security only to take actions to secure the border that are “necessary and appropriate”. These are the same words (in the opposite order) the US Supreme Court interpreted in Michigan vs EPA. As Scalia said, it would not be “appropriate” to “impose billions of dollars in economic costs in return for a few dollars” in benefits.

Trump’s proposed wall would certainly cost billions of dollars: He says $8 billion (Dh29.42 billion), while more realistic estimates put the price tag at $15 billion to $25 billion (and $500 million per year for upkeep).

What about the benefits of the wall? First, no matter how high the wall is, it won’t stop smugglers from tunneling underground. Moreover, the wall won’t stop a majority of unlawful immigrants, who now enter the US on visas that they overstay. Indeed, research indicates that border barriers are more likely to keep unlawful immigrants inside the country from exiting than to prevent people from entering.

Programme of mass deportation

Second, even if the wall does lower the number of unlawful immigrants in the US, the economic gains from reducing illegal immigration are not greater than the cost of the wall. Illegal immigrants pay billions of dollars in taxes, purchase goods and services and enhance American productivity in sectors such as agriculture. A 2012 study published by the Cato Institute concluded that gross domestic product would decline by roughly 1.5 per cent — or $2.6 trillion over a decade — if America pursues a programme of mass deportation and blocks undocumented immigrants from returning.

One of Trump’s major claims is that a wall would keep out illegal immigrants who commit violent crimes, but there is no evidence that illegal immigrants commit crime at a higher rate than citizens. Trump says that Mexico will pay for the wall, implying that the actual cost to the US will be zero. But the statute doesn’t authorise Trump to charge Mexico and Mexico says it will not pay. A judge would therefore give no weight to this argument.

A court challenge to Trump’s wallbuilding plans would need a plaintiff who meets the legal standing requirements. Plenty of people satisfy those criteria. Farmers in the Rio Grande Valley in Texas might sue on the ground that the wall would disrupt their water access. Or the state of California might sue to stop a wall-building effort that it thinks will hurt its own citizens.

Trump promises to appoint a US Supreme Court justice “very much in the mould” of Scalia. And yet Scalia’s costbenefit jurisprudence may put Trump in a bind. Applause lines at campaign rallies would not have swayed Scalia and will not impress current judges. If Trump wants to enact his agenda, he will need to drop the bluster and explain why his policies do more good than harm.

Daniel Hemel, Jonathan Masur and Eric Posner are professors at the University of Chicago Law School.