The third is that every statute that authorizes the executive branch to do something also puts limits on that power. Lawful executive action must respect those limits, what I call in my administrative-law classes an administrator’s “zone of discretion.” For example, the Census Act requires the secretary of commerce to submit, at least three years before the census date, a report containing the secretary’s “determination of the subjects proposed to be included in the census, and the types of information to be compiled.” The secretary must then submit, at least two years before the census date, a report containing the secretary’s “determination of the questions proposed to be included” in the census. Should the secretary of commerce decide just a year before the census date to ask each person his or her favorite Beatles song, the question would be impermissible because it was not reported to Congress in time.

Finally—and this is the speed bump over which the Commerce Department stumbled—under the federal Administrative Procedure Act, responsible officials must also, at the time a decision is made, offer a nonarbitrary, non-capricious explanation for choosing their strategy for carrying out their statutory authority. This requires at least that the proposed administrative action be a rational way of carrying out the mission Congress has assigned the executive, and that the rationale be clearly explained at the time of an agency decision. In the case of the citizenship question, the Department of Commerce failed to take this step, which is why a 2020 citizenship question is now on hold. Even if such a question could have been asked, in principle, consistent with the secretary’s zone of discretion, the failure of Commerce Secretary Wilbur Ross to offer a non-pretextual rationale for the citizenship question tripped him up in the courts. As euphemistically summarized by Chief Justice John Roberts for a Supreme Court majority, the secretary offered a “contrived … explanation for agency action that is incongruent with what the record reveals about the agency’s priorities and decision making process.”

The executive branch now has an obvious logic problem: It must generate a non-pretextual agency explanation to justify an action to which it already committed itself without any such explanation. The Justice Department’s public flailing-about for a new rationale looks like the very definition of “arbitrary and capricious.” But whether or not such a rationale can now be found and belatedly attached to the census question, a presidential order cannot make the job easier.

For one thing, a presidential order cannot expand the secretary’s zone of legal discretion to determine the contents of the census. Just as important, an executive order cannot relieve the commerce secretary of his obligation to proceed based on a nonarbitrary rationale rooted in his statutory mission. “The president wants me to ask this question” would not be an adequate reason. Nothing in the statute empowers presidential whim.