[Ed. – One man’s opinion.]
[Trump is] floating the possibility of declaring a state of emergency, using a “military version” of eminent domain to seize private land along the border, and building the wall without congressional consent. This would be a serious mistake — a lawless abuse of power that would almost certainly be blocked by the courts (including by Trump-appointed judges). In the remote chance it passed legal review, his declaration would have malignant effects on the American constitutional structure. He would enable future presidents to wield vast powers at a whim, shaking the president loose from his constitutional bonds once and for all.
The legal analysis here is relatively simple. The president does not have the constitutional or statutory authority to unilaterally declare an emergency under these facts, seize private land, and spend money to build a wall. The constitutional question was settled during the Korean War. At the height of the conflict — when the United States was locked in a grueling land conflict with hundreds of thousands of Chinese and North Korean troops — President Truman attempted to “take possession of and operate most of the nation’s steel mills” to avoid a strike by the United Steelworkers of America.