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In the weeks following his January 8th prime-time Oval Office address, we’ve repeatedly heard Trump rattle his saber – threatening the invocation of emergency powers to build ‘artistically designed steel slats’ to address the ‘humanitarian and security crisis at our southern border’. We heard him do so in his speech announcing the re-opening of the federal government. And now – the day after bipartisan negotiators reached a deal that would give him just a fraction of the money he’s sought to build his wall – he’s renewed the threat, saying: ‘I’m considering everything. While the dubious legality of any such action remains to be adjudicated, by any measure, it’s a very bad idea.

Article I, Section 8 of the Constitution empowers the Congress to raise and direct expenditure of public funds. The various Departments and Agencies of the executive branch – even the courts – must, for their part, make annual requests to Congress for the funding necessary to carry out their myriad activities. And, in authorizing such funds, the Congress places express conditions on what, where, and when, they can be spent.

It’s only under emergency circumstances that the President has the authority to override those authorizations. In particular, the National Emergencies Act of 1976 and the Military Construction Codification Act of 1982 empower the president to declare a state of emergency, and – upon doing so – divert funds from the Department of Defense military construction budget to emergency construction projects. Such a presidential declaration is appropriate only when the emergency ‘requires the use of the armed forces’, and the diversion of funds is limited to projects ‘essential to the national defense’.

Justifying circumstances include, for example, reinforcing national defenses against threatened invasion, and preparing coastal cities for – and helping them rebuild after – devastating hurricanes. And, any such diversion, in turn, puts in jeopardy funding for otherwise compelling military priorities – including hospitals, schools, and family housing; disaster relief, etc.

By any reasonable measure the current, historically low, flow of illegal immigrants crossing the southern border – which the U.S. Border Patrol is empowered to, and capable of handling – does not justify the invocation of this exceptional authority. Facts tell the story: Arrests at the southern border in 2018 (400,000) were roughly a quarter of what they were at their peak in 2000 (1.6 million); a 2017 State Department report found “no credible information that any member of a terrorist group has traveled through Mexico to gain access to the United States”; between 2007 and 2016 the number of unauthorized immigrants living in the U.S. has dropped from a peak of 12.2 million to 10.7 million; and, during this time, the number of Border Patrol agents has been doubled, and now stands at nearly 20,000.

There is no emergency; and the President's renewed threat to declare one should cause us all – regardless of political persuasion – to think long and hard about the precedent such a declaration could create, should it somehow survive certain legal challenge. Could the military be directed to construct low-income housing because a future president declares economic inequality to be an ‘emergency?’ Could the Army Corps of Engineers be directed to build solar farms because climate change is declared an ‘emergency?’ The ‘what ifs’ are countless and troubling.

A president declaring an emergency when one does not exist, and thereby exercising unchecked powers, is the real threat we face.

David B. Waller served as White House legal counsel to President Reagan; Assistant Secretary of Energy for International Affairs; and Deputy Director General and head of management of the International Atomic Energy Agency (IAEA) – during which time it received the Nobel Peace Prize. He is also a legal advisor for Republicans for the Rule of Law.