This did not go over well with the judicial panel. “By its plain terms, the statute refers to the simplicity of the pricing schedule as a whole,” Judge Neomi Rao wrote in the unanimous opinion. “It is not a provision about simple consumer prices, as suggested by the Postal Service.” Judge Rao quoted with approval Mr. Carlson’s arguments that consumers “may not appreciate the supposed ‘convenience’ of a higher price” and that “the public had never struggled to understand the price of stamps, even though that price had not been divisible by five for most of the nation’s history.”

It may bear mentioning that Judge Rao, who specialized in administrative law as a law professor, ran the Trump administration’s Office of Information and Regulatory Affairs before the president named her to the appeals court last November. Liberal groups opposed the nomination vigorously, with the Alliance for Justice labeling her a “slash-and-burn deregulator.” Another judge on the panel, Gregory Katsas, was deputy White House counsel early in the Trump administration. The third judge, Patricia Millett, named to the court by President Barack Obama, is a veteran of the solicitor general’s office in the Justice Department.

When I told colleagues that I planned to write in praise of the D.C. Circuit’s postal rate decision, some reacted with alarm. Didn’t I realize that this seemingly benign, even faintly amusing decision might just be a stalking horse for the big project of taking down the administrative state? That a court injecting itself into whether a stamp should cost 5 cents more, or 4, or 3 would, its appetite whetted, quickly move on to intervene in things that really matter?

Well, yes, that much is true. But it’s also true that a court acts as a guardian of democracy when it insists that executive branch actors give reasons that make sense for what they do. The Administrative Procedure Act, enacted in 1946, is the most important federal law that most people have never heard of. It’s a complex statute, but at its heart is a simple premise: that we the governed are entitled to something more than “because we say so” — whether the speaker is the Postal Regulatory Commission, the secretary of Homeland Security or the culture warriors within the Department of Health and Human Services who are carrying out their personal agenda of destroying the infrastructure by which government subsidizes birth control and reproductive health care for poor women.

The Administrative Procedure Act was the basis for injunctions issued this year by three Federal District Courts blocking the Trump administration’s reinterpretation of Title X to bar counseling on or referrals for abortion by health clinics that receive federal money. “An agency which changes its position must give a reasoned explanation for the change,” Federal District Judge Edward Chen wrote in one of those opinions. His 78-page opinion shredded the administration’s case for the new rule. For example, Judge Chen’s response to the administration’s assertion that “more patients could have access to services because of changes to the program” was blunt: “No explanation is offered for this conclusion, nor any analysis to support it.” An 11-judge panel of the United States Court of Appeals for the Ninth Circuit heard the administration’s appeal this week.