Roberts’ majority opinion in the DACA case (Department of Homeland Security v. Regents of University of California) takes a similar line. Roberts doesn’t claim that DACA can’t be rescinded. (Only Justice Sonia Sotomayor was persuaded that doing so would violate the Equal Protection Clause of the Constitution.) Instead, Roberts sides with U.S. District Judge John D. Bates in ruling that the administration’s original justification for the move (in a sloppy one-page memo by Sessions) was “arbitrary and capricious” under the Administrative Procedure Act (APA). He also labels arguments contained in a memo authored months later by Homeland Security secretary Kirstjen Nielsen “post hoc rationalizations.”

This doesn’t make Roberts a born-again partisan liberal. It makes him a defender of the rule of law and an institutionalist. How the federal government acts matters almost as much as, and sometimes more than, what it does. Laws, rules, and norms need to be followed. Decisions need to be explained and justified in ways that make sense. They can’t be arbitrary, capricious, or motivated by outright animus. And justifications can’t be fabricated after the fact in order to conceal the true motives of government officials. It doesn’t matter if the cause of such rationalizations is outright deception, as it was in the census case, or carelessness, as it likely was in the DACA case.

What the DACA decision also shows is that Roberts is alone among the court’s conservatives in caring about such issues. Justices Clarence Thomas, Samuel Alito, Neil Gorsuch, and Bret Kavanaugh all dissented in the DACA case, with the first three arguing that the Obama rule had always been illegal and Kavanaugh explicitly dismissing the majority’s concern with the APA’s “arbitrary and capricious” standard, denying its relevancy to the attempted rescission.