What’s next for the anti-Trump judicial resistance, now that the Supreme Court has curbed federal judges’ power to issue nationwide diktats known as “universal injunctions”? If the latest move by the American Civil Liberties Union is any guide, count on some of these judges — animated, it seems, by political animus toward the president — to embrace wider use of another legal tool, the class action, to accomplish the same obstructive ends.

Several of the high court’s conservatives appear to have anticipated, in the decision Friday in Trump v. CASA, that federal judges might attempt such a démarche. That’s the six-to-three decision, prompted by President Trump’s executive order curbing birthright citizenship, that the high court took as an occasion to find that judges’ use of universal injunctions exceeded their authority under law and the Constitution.

The opinion in CASA left the questions over birthright citizenship to be sorted out in lower courts, even as the Nine stripped judges of their power to wield the sweeping court orders. These broad orders, Justice Amy Coney Barrett writes, “were not a feature of federal court litigation until sometime in the 20th century.” Yet “by the end of the Biden administration,” nearly “every major presidential act” was “immediately frozen by a federal district court.” 

The universal injunctions became a particular scourge during Mr. Trump’s second term, in the first 100 days of which, Justice Barrett adds, “district courts issued approximately 25 universal injunctions.” Allowing district courts to issue these nationwide orders gave rise to what’s known as judge-shopping — picking a sympathetic jurist in whose court to file a federal case with national implications.

In some cases these nationwide injunctions helped Republicans. Feature, say, the litigation by which the Supreme Court put a halt to President Biden’s brazen student loan amnesty. Yet in recent months the use of these court orders appears to have taken on a political complexion, prompting Senator Grassley to gripe that they had become “a favorite tool for those seeking to obstruct Mr. Trump’s agenda.”

Now that the use of the universal injunction has been foreclosed, though, will federal judges turn to class actions? Such lawsuits group together individuals who have a common complaint or cause. Forging a class action, under federal law, requires the group to meet certain criteria. The group needs to be “so numerous,” federal procedural rules say, that bringing “all members” together “is impracticable.”

The group must share “questions of law or fact,” and the “claims or defenses of the representative parties” must be “typical of the claims or defenses of the class.” Last, representatives of the group must “fairly and adequately protect the interests of the class.” Meeting these criteria, legal sage Steven Vladeck says, is “no easy lift.” Yet it’s easy to envision sympathetic judges trying to facilitate formation of such classes in cases like, say, birthright citizenship.

Justice Samuel Alito cautioned against that in his CASA concurrence. “District courts,” he wrote, “should not view today’s decision as an invitation to certify nationwide classes without scrupulous adherence to the rigors” of federal rules on forming the legal groups. Yet wouldn’t you know but that the ACLU barely stopped for breakfast. It has already asked a judge to make the birthright case a class action.

Justice Brett Kavanaugh cautions, too, that individuals filing suits may “seek to proceed by class action” and “ask a court to award preliminary classwide relief that may be, say, statewide, regionwide, or even nationwide.” Yet “importantly, today’s decision will require district courts to follow proper legal procedures” when making rulings in such cases, and avoid offering “relief” to those filing suits unless it “is legally authorized.”

The ACLU’s request is before Judge Joseph LaPlante in New Hampshire. He was among those who issued a universal injunction against Mr. Trump’s birthright citizenship policy. If he ignores Justice Alito’s warning, it could well vindicate the jurist’s fear that universal injunctions could “return from the grave under the guise of ‘nationwide class relief,’” and Friday’s ruling by the Nine “will be of little more than minor academic interest.”