In 1974, the Supreme Court seemingly approved a special prosecutor’s authority in then-President Richard Nixon’s case over the Watergate tapes subpoena. But in dismissing the classified documents case against Donald Trump on Monday, U.S. District Judge Aileen Cannon rejected language from that Supreme Court ruling to find that Jack Smith was unlawfully appointed as special counsel against the former president.

How could she have done so?

Putting aside for a moment that she may be reversed on appeal, the answer lies in something called dicta, meaning language in an opinion that isn’t necessary to the ruling. Cannon deemed the language at issue from the Nixon case to be that sort of statement that isn’t binding precedent.

Here’s the relevant passage from United States v. Nixon in 1974 that she excerpted in her ruling dismissing Trump’s indictment:

Under the authority of Art. II, § 2, Congress has vested in the Attorney General the power to conduct the criminal litigation of the United States Government. 28 U.S.C. § 516. It has also vested in him the power to appoint subordinate officers to assist him in the discharge of his duties. 28 U.S.C. §§ 509, 510, 515, 533. Acting pursuant to those statutes, the Attorney General has delegated the authority to represent the United States in these particular matters to a Special Prosecutor with unique authority and tenure. The regulation gives the Special Prosecutor explicit power to contest the invocation of executive privilege in the process of seeking evidence deemed relevant to the performance of these specially delegated duties.

Cannon emphasized that “the focal point of the parties’ dispute” regarding Smith’s appointment is the line: “It has also vested in him the power to appoint subordinate officers to assist him in the discharge of his duties. 28 U.S.C. §§ 509, 510, 515, 533.” She noted the defense argued that the language from Nixon about the attorney general’s authority “is non-binding dictum and thus should not control the Court’s statutory analysis,” while Smith said that it was necessary to the case’s holding and is therefore binding on lower courts.

Rejecting Smith’s approach, Cannon wrote that the attorney general’s authority in the Nixon case “was not raised, briefed, argued, or disputed before the Nixon Court” and that the Supreme Court at most assumed that the attorney general had authority without expressly ruling on it. Therefore, the Trump appointee wrote, “Nixon’s passing remarks on that point are not binding precedent.”

Cannon further said that she disagreed with rulings from the D.C. federal appeals court that approvingly cited Nixon, including a 2019 ruling against a challenge to special counsel Robert Mueller’s appointment. Cannon sits in a different federal circuit (the 11th, which reversed her during previous Trump-related litigation), so she isn’t bound by D.C. Circuit precedent.

Notably, Cannon cited Justice Clarence Thomas’ concurrence from the immunity ruling in Trump’s favor earlier this month, where Thomas said that the Nixon case only “gave passing reference to the cited statutes” and “provided no analysis of those provisions’ text.” No other justices joined Thomas’ concurrence, but the appointment issue wasn’t directly before the justices in the immunity case, so we don’t know how they would rule if the issue were argued before them. Thomas had joined Chief Justice John Roberts’ opinion bestowing broad criminal immunity but wrote separately to raise the appointment issue.

Ultimately, the Supreme Court may have to weigh in on what its own precedent means. Of course, if the appointment issue gets to the high court, the question isn’t only what a majority of the court thinks Nixon meant, but, perhaps more importantly, what a majority of the court wants to do in Trump’s case today. The immunity ruling reminds us that, especially in cases involving presidential power, we’ll never know for sure what the court will do until it rules.

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