When a court seeks the “single, best meaning” of a statute, should it be limited to considering the interpretations that parties to the litigation choose to offer? Justice Alito’s dissent in Trump v. Illinois seems to suggest it should. This post explains why, and considers the implications of such a view for statutory interpretation in a democracy.

Trump v. Illinois is a short per curiam from the emergency docket issued on December 23, 2025. As numerous others have explained, the opinion let stand a lower court order preventing the Trump Administration from deploying federalized National Guard members to Illinois. The opinion explained that 10 U.S.C. § 12406(3) “empowers [the President] to federalize members of the Guard if he is ‘unable with the regular forces to execute the laws of the United States.’” Asserting authority under this provision, the President “called 300 members of the Illinois National Guard into active federal service to protect federal personnel and property in Illinois.” A district court issued a temporary restraining order. On appeal, the Seventh Circuit allowed federalization but upheld the prohibition on deployment. On the emergency docket, the Supreme Court, perhaps spurred by an amicus brief by Professor Martin Lederman, asked the parties for supplemental briefing on the meaning of “regular forces” in § 12406(3).

Lederman’s amicus brief argued that “regular forces” meant the military—not, as the decisions below had assumed, civilian law enforcement. On this reading, the President cannot federalize the National Guard until he has tried and failed to enforce the laws with the military. That use of the military is governed by a separate set of requirements under the Posse Comitatus Act—requirements that the Trump Administration had not even attempted to fulfill. In the supplemental briefing, Illinois argued that “regular forces” did indeed refer to the military; the federal government argued it meant civilian law enforcement. The per curiam ended up going with the military interpretation, concluding that the statute likely did not allow the President to federalize and deploy National Guard troops under the circumstances of this case.

Justice Alito, joined by Justice Thomas, dissented on several grounds; Justice Gorsuch, dissenting separately, echoed Justice Alito’s statutory interpretation arguments. Justice Alito’s dissent takes the per curiam to task for considering arguments about the meaning of “the regular forces” that were not offered by the parties below (or, indeed, in regular briefing). It was only after the Court teed up the issue by requesting supplemental briefing on this specific question that Illinois got the hint and made the argument. The dissent argued that the per curiam violated the “party presentation principle”: the adversarial tradition that courts consider only arguments proffered by the parties, and treat arguments that parties have not presented as waived or forfeited.  

Litigants take statutes to court for different reasons. They might ask the court to apply a statute (whose meaning is assumed); to interpret a statute (whose meaning is disputed); or to judicially review a statute (whose constitutional validity is at issue). When a court simply applies a law, the party presentation principle is relatively straightforward (if perhaps kind of harsh): if the litigant doesn’t invoke some way of applying a statute that benefits her, neither will the court. So, say a plaintiff seeks compensation for the unauthorized use of his intellectual property that caused him no economic harm. He might still be potentially entitled to a royalty—but if doesn’t ask for the royalty, the court is not supposed to grant him one sua sponte. In this example the court is not deciding what the legal principle of “royalties” entails. It’s just saying that the plaintiff doesn’t get a royalty because he failed to ask for one, and that decision only affects the parties to the litigation.

In the realm of judicial review, the party presentation principle is a little wonkier. You might think that whether a statute is constitutionally sound wouldn’t depend on whether a litigant has argued it isn’t, but a 2020 opinion by Justice Ginsburg thinks otherwise. In United States v. Sineneng-Smith, a unanimous Court reversed a Ninth Circuit invalidation of a federal statute for overbreadth. The opinion chided the appeals panel for raising the overbreadth issue itself in a supplemental briefing request, rather than sticking to the parties’ original dispute about whether the statute violated the First Amendment’s free speech guarantee. Unlike the statutory application context, applying the party presentation principle to judicial review cases has effects beyond the parties: a potentially unconstitutional statute might stay in effect longer. Still, the party presentation principle does not foreclose a later litigant from raising a constitutional problem with that statute. Having been evaluated on one constitutional basis does not mean that the statute can’t be evaluated on another basis later on.

Justice Alito’s dissent, however, does not limit the party presentation principle to statutory application and judicial review. It extends the principle to decisions about the statute’s meaning across all cases. This suggestion is particularly striking in light of the current corpus juris. Less than two years ago, Justice Alito joined the majority in Loper Bright v. Raimondo, which held that a statute has a “single, best meaning” that it is a court’s job to determine.[1]

Putting these two positions together yields a statutory interpretation theory of sorts: (1) a statute has a single, best meaning that a court must find by (2) choosing from among the meanings proposed by parties to a lawsuit that requires the court to interpret the statute. To interpret the statute, the court should not use material beyond what the litigants—named parties, mind you, not amici—offer.

Justice Alito does not provide any reason to think that parties to litigation would necessarily argue for the single, best meaning of a statute. And indeed, it seems a little unlikely. Parties litigate for their own reasons and argue in their own interests. They may (and usually will) press an understanding of a statute that works in their interests even if it does not present the best reading of the law. If none of the interpretations that benefit the parties to some particular lawsuit involve the single, best meaning of the law, then it’s quite likely that no party to that lawsuit will argue for it. This, too, is the adversarial system at work.

Yet Justice Alito’s dissent would limit courts to the self-interested interpretations offered by parties to that litigation. That would allow private parties to determine the meaning—or at least the scope of permissible meanings—of the law for all of us. Even a later litigant who pressed the single, best meaning in a later case could be out of luck: binding precedent might already have settled on a statutory meaning from the menu of suboptimal options offered by the first parties to get the court’s ear. Justice Alito’s theory, in short—apparently shared by Justices Thomas and Gorsuch—outsources power over the meaning of a generally applicable law to particular litigants in a particular lawsuit. Unlike in the statutory application context, this interpretation would apply for everyone, not just parties to the litigation. And unlike in the judicial review context, because of the way precedent works and Loper Bright’s insistence that statutes have single, permanent meanings, the court in this situation will have already laid down the statute’s meaning for later courts.

Of course, it’s just the emergency, or shadow, or interim, docket; nothing is final yet. Maybe Justice Alito’s argument should be read to imply (sub silentio) that this theory holds only for non-merits orders, to be abandoned if the Court later gets to the merits. Yet it’s not clear how the supposedly provisional nature of a ruling would make its use of a statutory interpretation theory provisional. If a statute has a single, best meaning, presumably a court must adjudicate on that meaning’s basis. What authorizes a court to ignore the single, best meaning when adjudicating an emergency order? If it does, the court might, however provisionally, make a decision based on an incorrect interpretation of the law—maybe even an interpretation the court knows to be wrong. And of course, there’s many a slip ’twixt the cup and lip: we don’t know how long an order in an emergency application will stand, nor whether the Court will ever get to the merits. That faulty statutory interpretation might hold for a good while yet. That’s just as problematic for an interim decision as for a final one.

Placing the Trump v. Illinois dissents in their legal context, then, yields a theory that leaves it to fortuitously situated litigants, rather than judges, to determine what a law can mean. At the same time, as others have noted, Justice Alito’s insistence on the party presentation principle has been selective. After all, he wrote the opinion overturning Roe v. Wade—a result no party had suggested below (or at all, until Justice Barrett was appointed).[2] So perhaps the dissenting Justices press for party presentation here not as a principle they would apply across cases, but as an expedient to yield a result they prefer. Unfortunately, neither of these options comports very well with the rule of law.

Anya Bernstein is Jesse Root Professor of Law at the University of Connecticut School of Law.

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[1] As I have written elsewhere, I think this holding misconstrues how regulatory statutes and the regulatory agencies that effectuate them work.

[2] As Benjamin Johnson has noted, the Supreme Court regularly decides which questions it wants to answer in adjudication rather than simply responding to litigant queries; as far as I know, none of the dissenting Justices here have consistently opposed this practice.