In sum, a president has the discretion to declare an emergency, not to create one. This distinction is critical. Congress did not attempt to define what constitutes an “emergency,” but this is not evidence that it left the choice without limits to the president. Rather, as one commentator wrote, the absence of a definition reflected “the assumption … that genuine crisis is readily identifiable by everyone in the polity.” Hence the law’s reference to “the period of a national emergency,” which would be clear to all, and which would then—and only then—be subject to the president’s declaration at his or her discretion.

Read: What the president could do if he declares a state of emergency

This is the reading most consistent with the plain wording of the law but also with Congress’s reasons for enacting the statute: Concern about the adequacy of controls on the presidents’ invocation of emergency powers. Among the limits the legislature devised was automatic termination of an emergency one year after it was declared, subject to the president’s choice to renew it. Congress also specified a procedure by which it could approve joint resolutions to terminate an emergency at any time.

Nothing in the statute or the legislative history suggests that in the event Congress did not resort to these controls, the president was free to do as he wished. It is, in fact, inconceivable that in 1976, when Congress enacted the statute, it was providing carte blanche to the president to ignore the separation of powers and spend freely anytime Congress somehow failed to take the procedural measures to stop him.

After all, Congress then, as now, faces the normal collective-action problems in responding speedily, not to mention on the pace a president can set. A president can declare an emergency, and immediately exercise the special authorities that this declaration affords, much faster than Congress could be expected to act to consider, and if it chooses, to rein in the executive. Congress surely knew this much when it was legislating on these matters in reaction to the imperial presidency in the aftermath of the Vietnam War and Watergate.

Moreover, the suggestion that congressional execution of the joint resolution is the only check on the president requires imagining that Congress fell into a trap of its own making. The statute provides that even if Congress acts to terminate an emergency, the termination will not affect “any action taken or proceeding pending not finally concluded or determined on such date [of termination]” or “any action or proceeding based on any act committed prior to such date.” In other words, some of what the president has done by the proclamation of an emergency cannot be undone. Congress will always have to play catch-up and can never fully catch up.

This is not a reasonable reading of the statute, nor is it an appropriate assumption about Congress’s protection of its own constitutional authorities. It is critical to bear in mind what is at stake here: Congress has exclusive control of the power to appropriate. The expenditure of federal funds without lawful congressional authorization is a criminal offense. Congress could have written into the law the president’s unfettered discretion to determine the existence of an emergency. It did not. Courts will not lightly read into the law what Congress does not expressly provide on an issue central to the constitutional separation of powers.