An extraordinarily acrimonious exchange between Justices Amy Coney Barrett and Ketanji Brown Jackson underscores that tensions, now erupted, are roiling the Supreme Court as it closes its term. 

The confrontation between the two most junior justices came in Trump v. Casa, a case that arose from the president’s executive order abolishing birthright citizenship. The high court ultimately ruled not on the merits of that action, but rather on whether district court judges can issue so-called nationwide injunctions that apply not only to the parties before them but to all of America. 

The parade of district-level judges issuing nationwide blocks on Trump executive actions — thereby slowing the president’s agenda while government attorneys pursued appeals — has enraged the White House, which contends that the issuing of such orders has skyrocketed during the first months of Mr. Trump’s second term.

Now, by a six-to-three vote, the Nine upended the ability of lone judges to issue rulings that bind a nation. That means that the ban on birthright citizenship is set to go into effect everywhere it has not been explicitly frozen. The high court, though, did grant a 30-day delay on its ruling taking effect, which could give challengers to the law time to craft class actions. 

The majority opinion, which could prove a boon to Mr. Trump’s ability to advance his agenda in the face of judicial recalcitrance, was written by Justice Barrett. Nominated to the Supreme Court by Mr. Trump, she has come under sustained criticism from precincts of his MAGA base for occasional rulings against the administration in cases relating to deportation of illegal immigrants and the White House’s efforts to freeze federal spending.

Justice Barrett has frequently come through for conservatives on signature cases — siding with Mr. Trump on presidential immunity, striking down racial preferences in college admissions, supporting bans on medical gender treatments for minors, and overturning Roe vs. Wade, among other key rulings.

Yet she also confounded some on the legal right when she recused herself from deciding a case, Oklahoma Statewide Charter School Board v. Drummond, that centered on the creation of America’s first religious charter school. Her recusal — for reasons unclear — left the court deadlocked four to four, and preserved the ruling of the Oklahoma supreme court that such a school would be crosswise with the Constitution.

Justice Jackson is President Biden’s sole Supreme Court pick. In her own personal dissent in Trump, she reckoned that the majority’s opinion “gives the Executive the go-ahead to sometimes wield the kind of unchecked, arbitrary power the Founders crafted our Constitution to eradicate.” 

Justice Jackson adds: “It is not difficult to predict how this all ends. Eventually, executive power will become completely uncontainable, and our beloved constitutional Republic will be no more.” 

That sharp language from Justice Jackson came on the heels of her issuing a rebuke to the majority in two other decisions released this week. In Stanley v. City of Sanford she called the majority “narrow-minded” and “stingy” for narrowing access to the Americans with Disabilities Act. In Diamond Alternative Energy v. Environmental Protection Agency, she alleged the court was a partisan of “moneyed interests.”

Earlier in the term Justice Jackson accused her conservative colleagues of “unleashing devastation” based on their handling of the Supreme Court’s emergency or “shadow” docket. Here, though, it is Justice Barrett who calls Justice Jackson’s argument “extreme” and a “startling line of attack.” Justice Jackson calls the court’s decision an “existential threat to the rule of law.”  

To that Justice Barrett writes, “We will not dwell on Justice Jackson’s argument. … We observe only this: Justice Jackson decries an imperial Executive while embracing an imperial Judiciary. No one disputes that the Executive has a duty to follow the law. But the Judiciary does not have unbridled authority to enforce this obligation—in fact, sometimes the law prohibits the Judiciary from doing so.”

Worth noting is that all six of the conservative justices signed on to the entirety of Justice Barrett’s opinion, meaning that they all endorsed her broadside against Justice Jackson. In contrast, Justice Sonia Sotomayor in Stanley refused to sign on to Justice Jackson’s most acerbic criticism of the court’s majority, though she did endorse the rest of her liberal colleague’s dissent.

Justice Barrett’s judgment that Justice Jackson’s position is “at odds with more than two centuries’ worth of precedent, not to mention the Constitution itself,” is the kind of blunt retort rarely seen in the usually genteel world of Supreme Court opinion writing. It is also noteworthy, the legal sage Joshua Blackman tells the Sun, that increasingly Justices Sotomayor and Kagan are declining to endorse Justice Jackson’s dissents. 

Mr. Blackman adds that Justice Jackson’s apparent disdain for conciliation could be seen by the court’s more senior liberals as counterproductive, especially as Justice Barrett has at times appeared interested in serving, alongside Chief Justice Roberts, as something as a swing vote. Mr. Blackman, a critic of Justice Barrett, nevertheless acknowledges that she “doesn’t allow herself to get pushed around.”