Does President Donald Trump have the legal authority to declare a national emergency, and order the military to build a wall between Mexico and the United States?

We are dealing with a novel question here, which means that any judgment has to have a degree of tentativeness. But the best answer appears to be no.

Outside of the most extraordinary circumstances, the US Constitution does not give the president “emergency power.” If he wants to declare a national emergency -- to build a wall, to respond to climate change, to combat poverty, or anything else -- he must rely on congressional enactments.

It’s not entirely clear that courts would uphold the president’s declaration of a national emergency, but for purposes of discussion, let’s assume they would. Any court would hesitate before second-guessing his judgment.

But here’s a crucial point: After the president declares a national emergency, it does not follow that he can do anything at all. The declaration merely triggers, or unlocks, a large number of specific authorities.

For the president, the most relevant of these has an encouraging name: “Construction Authority in the Event of a Declaration of War or National Emergency.”

This provision says that if the national emergency requires the use of the armed forces, the secretary of Defense “may undertake military construction projects” -- even if those projects are “not otherwise authorized by law,” so long as they “are necessary to support such use of the armed forces.” Importantly, the projects “may be undertaken only within the total amount of funds that have been appropriated for military construction.”

At first glance, that provision might seem to authorize the defense secretary to order the military to build a wall. But what’s a military construction project? Can it really include a wall between the US and Mexico? We have to do a little work to answer that question -- but it probably can’t.

A separate provision defines military construction as “any construction, development, conversion, or extension of any kind carried out with respect to a military installation, whether to satisfy temporary or permanent requirements, or any acquisition of land or construction of a defense access road.”

So now we need to know what a “military installation” is. Under the law, it is “a base, camp, post, station, yard, center, or other activity under the jurisdiction of the Secretary of a military department.”

Congress even provided a definition of a military construction project: military construction work “necessary to produce a complete and usable facility or a complete and usable improvement to an existing facility.”

That’s a lot of words. But the most natural reading doesn’t help Trump.

After the president has declared a national emergency, and if the armed forces are required, the defense secretary can use the military to build bases, camps, yards and other areas for military use. Under the law, military construction projects must be “necessary to support” the “use of the armed forces.”

If the military is deployed to some area, soldiers need to have bases and camps. That includes “a defense access road,” so that they can get there in the first place (and also leave).

But that doesn’t mean that the defense secretary can use appropriated funds to build a wall (or fence) between the United States and Mexico! Such a wall just isn’t a “military construction project” within the meaning of the law.

To be sure, it is reasonable to say that the secretary can build a wall with the specific goal of defending military bases. But that’s a lot different from saying that he can build a wall to try to prevent people (including criminals), from coming into the US.

For Trump, a separate law, called Reprogramming During National Emergencies, might seem more promising.

When a national emergency has been declared, the defense secretary is authorized to “terminate or defer the construction, operation, maintenance, or repair of any Department of the Army civil works project that he deems not essential to the national defense.” He can decide to apply the resources for that project “to construct or assist in the construction, operation, maintenance, and repair of authorized civil works, military construction, and civil defense projects that are essential to the national defense.”

That seems to mean that if the president declares a national emergency, he can divert funds from current civil works projects that he does not deem essential to the national defense to other projects that he does deem essential.

Perfect, yes?

Actually not. The first problem is that a wall between Mexico and the US would have to be deemed “essential to the national defense.” If the goal is to prevent a military invasion, that’s easy. But if the goal is to respond to a supposed influx of drugs or criminals or to a humanitarian crisis, that’s a tough argument to make.

The second problem is that Congress would have to have already “authorized” the wall. To say the least, it isn’t clear that it has done that.

In any administration, the president’s lawyers are occasionally put in an awkward position. Their boss really wants them to say “yes,” but the right answer is “no.”

With respect to declaring a national emergency and building the wall, that looks like the right answer.


Cass Sunstein
Cass R. Sunstein is a Bloomberg Opinion columnist. He is the author of “The Cost-Benefit Revolution” and co-author of “Nudge: Improving Decisions About Health, Wealth and Happiness.” -- Ed.

(Bloomberg)