Can Trump Really Declare A National Emergency For The US-Mexico Border Wall?

After failing to secure the requested funding for hundreds of miles for a border wall, President Donald Trump on Friday declared a national emergency, raising numerous constitutional authority questions as well as potentially creating a precedent for the executive branch's power to unilaterally achieve a policy goal.

The Homeland Security appropriations bill provides $1.375 billion for border security but the White House is seeking more than $6 billion in funding through the national emergency.

Acting White House Chief of Staff Mick Mulvaney told reporters that funding will come from several sources such as $3.6 billion in military construction money allocated by Congress for other projects. Another $2.5 billion will come from the Department of Defense's drug interdiction program and $600 million from the Treasury Department's drug forfeiture fund.

The decision to move billions from other federal coffers is expected to set off legal challenges.

In an appearance Friday on CNBC, Hugh Hewitt, a conservative talk show host and Chapman University law professor, suggested Trump could win court challenges by using a creative legal argument.

"There have been a lot of unilateral executive actions in American history beginning with the Louisiana Purchase by [President Thomas] Jefferson, [President Abraham Lincoln's] Emancipation Proclamation, all the way through [President] Bill Clinton's bombing of Iraq in 1998 and President [Barack] Obama's bombing of Libya in 2012," Hewitt said. "What happens in each of these [cases] is they are subjected to what is known as 'the Justice Jackson test.'"

Hewitt explained that the Justice Jackson test, which involved Supreme Court Justice Robert Jackson's opinion in a 1952 case, "Youngstown Sheet & Tube Co. v. Sawyer." Jackson presented three categories for the exercise of presidential power.

"I do believe if the lawsuit is brought even in the Fifth Circuit, the president might win at the appeals level. He certainly would have a good shot at winning at the Supreme Court," Hewitt said.

Hewitt did not offer a prediction as to whether Trump would prevail in the courts and many expect a long legal battle to ensue.

"Everyone’s going to come out of the woodwork," Stephen Vladeck, a University of Texas law professor who teaches national security law, told USA Today. "I think we’re going to see an array of lawsuits that actually would all have to be dealt with separately."

Citizens for Responsibility and Ethics in Washington (CREW) and the American Civil Liberties Union (ACLU) have already filed lawsuits over the national emergency declaration.

In an appearance on "PBS News Hour," Leon Panetta, a former Defense Secretary and director of the Office of Management and Budget, raised questions as to whether Trump can declare a national emergency for a campaign promise.

"There's no question that presidents have the authority to declare a national emergency," Panetta said. "And when past presidents have used that authority, both the House and the Senate have gone along with it, because they were legitimate national emergencies.

"In this case, there's a lot of questions as to whether or not this constitutes a national emergency. If it was a national emergency, why didn't he declare it a national emergency last year, when he was talking about the need for a wall?"

According to a Pew Reseach Center report released in November, the estimated number of undocumented immigrants living in the U.S. reached a 12-year low in 2016.

"This year, looking at all the statistics, the numbers of people coming across the border has gone down. The enforcement has gone up. Generally, it's a hard case to make that it constitutes the kind of a national emergency that would be able to support the president's move here," Panetta said.

In an opinion piece in USA Today, George Mason University law professor Ilya Somin cited how Trump's national emergency ploy could set a precedent for using vague security pretext to authorize sweeping executive powers.

"If Trump succeeds in using emergency powers to build the wall and seize property through eminent domain, future presidents could exploit this dangerous precedent. They, too, could declare a 'national emergency,' and then divert military funds and take private property without congressional authorization," Somin wrote.