Of course, Trump’s hesitation also belies his claim that there is an emergency at the border. Presidents don’t dawdle in the face of real emergencies. President George W. Bush did not spend weeks scratching his head about whether to issue an emergency declaration after the terrorist attacks of 9/11. But even if a real crisis existed, emergency powers are designed for situations in which Congress has no time to act. If Congress does have time, then there is no justification for bypassing the ordinary legislative process.

Indeed, the more time Congress has to act—and the more times it votes against providing the funding the president has asked for—the clearer it becomes that an emergency declaration in this case would be designed as an end-run around the Constitution. Article I provides that “No money shall be drawn from the treasury, but in consequence of appropriations made by law.” This provision is one of the Constitution’s most important checks against executive-branch overreach. Congress has now consistently declined to appropriate funding for the border wall. Whatever deference judges might owe to the president’s assessment of what constitutes an emergency, an interpretation of the National Emergencies Act that would allow the president to engage in an expenditure of funds for which Congress has expressly withheld consent cannot be squared with the Constitution.