In joining with the Supreme Court's four liberal justices to block Trump administration plans to end the Deferred Action for Childhood Arrivals, or DACA, program (which was instituted by Barack Obama to protect immigrants brought to the United States as children from being deported), Chief Justice John Roberts has shown that he's had quite enough of the mendaciousness that marks so much of what the Trump administration has tried to do over the past three years.

As The Atlantic's Adam Serwer pointed out in a perspicacious tweet shortly after the 5-4 ruling was announced, Roberts' "very dim view of the Trump administration's bad faith" goes back to the census case, Department of Commerce v. New York, from the Supreme Court's last term. That's when the court was asked to rule on whether the administration could add a citizenship question to the 2020 census.

The plaintiffs in that case, as Slate's Mark Joseph Stern explained in his book American Justice 2019: The Roberts Court Arrives (which I had a hand in publishing), uncovered convincing evidence that "the true purpose of the citizenship question was to favor white Republican voters" (by discouraging undocumented immigrants from completing the census, thereby lowering population numbers, representation, and federal funding for areas of the country with greater numbers of immigrants, which tend to vote for Democrats). But when Commerce Secretary Wilbur Ross announced his rationale for adding the census question, he justified it in terms of a need for the government to do a better job of enforcing the Voting Rights Act (VRA). What the plaintiffs in the Supreme Court case later discovered is that this rationale was pretextual — deliberately concocted by a Justice Department lawyer after then-Attorney General Jeff Sessions asked him to work with the Commerce Department to do precisely that.

Ross knew very well that the question was being added to advantage Republicans, but he devised a deception to conceal it.

On substance, Roberts had no objection to the Trump administration adding a citizenship question to the census. Interestingly, the bulk of his majority opinion joining with the high court's four liberal justices in blocking the question read like it was written to justify siding with the court's four conservatives in permitting the question. Yet in the last section of the opinion, Robert changed tack, writing that government agencies must "disclose the basis" of their actions and not engage in post hoc rationalizations to justify them. Judged by that standard, the government had failed in this case.

As Roberts wrote at the conclusion of his opinion,

Altogether, the evidence tells a story that does not match the Secretary's explanation for his decision. Unlike a typical case in which an agency may have both stated and unstated reasons for a decision, here the VRA enforcement rationale — the sole stated reason — seems to have been contrived. The reasoned explanation requirement of administrative law is meant to ensure that agencies offer genuine justifications for important decisions, reasons that can be scrutinized by courts and the interested public. The explanation provided here was more of a distraction.

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.

But the chief justice has other concerns, among them the need to uphold certain procedural standards across the federal government. Presidents and their appointees can't simply do anything they want, even when the aim falls within their purview. They need to abide by the rule of law in taking action. That leaves open the possibility of the Trump administration trying again in a more cautious and careful way. If the administration does that, Roberts may well sign off on a rescission of DACA.

The demand that it be done by the book is not nothing. In fact, it's what separates a nation governed by law from one ruled by the whims of a malicious despot and his obsequious enablers. We should be grateful that John Roberts understands the difference.

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