[Future Snake Eater]

Huh? How does one “do a national emergency”? It exists or it doesn’t.

Not when it's an executive process requiring a formal declaration.

[plain talk]

Correct. A President can issue a formal declaration confirming that a national emergency exists. But that’s not what Trump said. Trump discussed “doing” a national emergency. A President doesn’t “do” an emergency. The emergency either exists or it doesn’t.