Earlier this month, the Supreme Court held in Wooden v. United States that ten counts of burglary committed on the same night at the same storage facility occurred on the same “occasion” for purposes of the Armed Career Criminal Act (ACCA). Although unanimous with respect to the outcome, the Court fractured with respect to rationale. The justices’ five separate opinions give those of us who work on statutory interpretation plenty to ponder. Below, I share a few thoughts, focusing on issues of vagueness, the grounds of “substantive canons,” and the precedential effect (or lack thereof) of judges employing a given interpretive methodology.

William Wooden broke into a storage facility one night and stole from ten of its storage units. He subsequently pleaded guilty to ten counts of burglary, one per storage unit. Many years later, he was convicted of being a felon in possession of a firearm, and the prosecution sought an enhanced penalty under the ACCA, which mandates a fifteen-year minimum sentence for offenders with three prior convictions for violent felonies “committed on occasions different from one another.” The issue was whether Wooden’s ten burglary convictions were committed on different occasions. The district court held that they were, and the Sixth Circuit affirmed, reasoning that the elements of each of conviction were satisfied at distinct moments in time.

Justice Kagan—joined, in full or in part, by all but Justice Gorsuch—wrote for the Court, reversing the Sixth Circuit. She began with the “ordinary meaning” of the word “occasion.” An ordinary person, she reasoned, would speak of a wedding (including the ceremony and reception) as one occasion. Less happily, an ordinary person would speak of a barroom brawl (including punches thrown at several persons) as one occasion. So too, it is natural to speak of Wooden’s crimes as having been committed on a single occasion, given their (i) timing (one night), (ii) location (one facility), and (iii) interrelationship (all were part of a single scheme).

In addition—and Justices Thomas, Alito, and Barrett did not join this part of the opinion—Justice Kagan looked to the legislative history and purpose of the relevant provision. She contended that Congress amended the ACCA to add the “occasions” clause in response to the Eighth Circuit’s decision in United States v. Petty, which had held that several counts of robbery committed on the same day in the same restaurant triggered the ACCA’s mandatory minimum. Moreover, the ACCA’s purpose is to address the “special danger” posed by career criminals, and Wooden’s activities hardly amounted to a career in crime. One night does not a career make.

Justice Kagan’s reasoning was predominantly textualist, appealing to how a reasonable reader would have most likely understood the statutory provision, so it is perhaps surprising that Justice Gorsuch did not join any part of her opinion. His objection was that her multi-factor balancing test—looking to crimes’ timing, location, and interrelationship—gave future courts too little guidance on what counts as an “occasion.” Would selling drugs “to the same undercover police officer twice at the same street corner one hour apart” count as occurring on one occasion? What about assaulting one victim inside a bar and then another victim twenty minutes later outdoors?

Here, Justice Gorsuch displays the sort of preference for “rules” over “standards” that sometimes accompanies textualism. I am generally a fan of rules over standards myself. Still, I do not feel the force of Justice Gorsuch’s worry in this case. The word “occasion” is vague. It has a definite extension (events that clearly count as an occasion) and a definite nonextension (events that clearly do not count as an occasion). But it also admits of borderline cases (events for which there is no fact of the matter as to whether they count as an occasion). Moreover, there is the problem of higher-order vagueness: no doubt, there are borderline cases of borderline cases.

Rather than fleshing out “occasion” as the majority did, Justice Gorsuch would have decided the case by appealing to the rule of lenity and thus resolving the statutory-interpretation question in Wooden’s favor. But does that approach provide any more guidance to lower courts? Perhaps some, but my sense is not much. Justice Gorsuch gives example of borderline cases, but some borderline cases are inevitable. More to the point, the triggering condition for the rule of lenity—“ambiguity,” or unclarity, in statutory meaning—may not be all that much easier to agree upon than whether a sequence of events counts as a single occasion.

Justice Kavanaugh wrote separately solely to express his disagreement with Justice Gorsuch. According to Justice Gorsuch, the triggering condition for lenity is “ambiguity;” according to Justice Kavanaugh, it is something more stringent—“grievous ambiguity.” This is not the first time that Justice Kavanaugh has made this point (see his concurrence in Shular v. United States). Behind these opinions lies his longstanding suspicion of all ambiguity-dependent canons of interpretation. Back in 2016, then-Judge Kavanaugh published a book review calling on courts to “reduce the number of canons of construction that depend on an initial finding of ambiguity.”

The rule of lenity is a closure rule: its function is to reduce indeterminacy in the law stemming from unclarity in criminal statutes’ meaning. It is an important moral-political question how quick judges should be to rely on such closure rules (not just the rule of lenity but also Chevron, etc.) in place of other means of proceeding (e.g., looking to the statute’s purpose or to how a reasonable reader would have been most likely to understand it). Judges vary widely in how quick they are to invoke such closure rules, and their use of words like “unambiguous” or “plain” may cloak controversial normative judgments about when resort to such rules is appropriate.

But what most interests me about the Gorsuch-Kavanaugh exchange is that it highlights a jurisprudential question concerning what grounds the legality of the rule of lenity and other “substantive canons.” Justices Gorsuch and Kavanaugh each cited Supreme Court precedents employing their preferred formulation of the rule. Justice Kavanaugh relied on more recent cases (though it seems that none of these purported to change the rule). By contrast, Justice Gorsuch relied mostly on earlier cases, claiming that the more recent ones speaking of “grievous ambiguity” were out of the “mainstream” and lacked a “well-considered theory about lenity.”

It seems that the legality of common-law rules like rule of lenity is not grounded in any one judicial decision but rather in a string of decisions. Since Justices Gorsuch and Kavanaugh could each cite a string of decisions employing their preferred formulation of the rule, does it follow that it is indeterminate which formulation is part of our law? In other words, is it determinate that some rule of lenity is part of our law but indeterminate what exactly the rule is? That seems right, at least on the sort of positivist theory of law that I favor. But perhaps one could argue that the correct formulation is that which occurs most often (or perhaps most recently) in the caselaw.

Matters are different when it comes to the legality of other common-law rules. When courts interpret legal texts and thereby interstitially make law, the legality of the new rule is grounded in a specific decision. Thus, the legality of the rule “Courts must look to the timing, location, and interrelationship of crimes to determine whether they count as occurring on a single occasion for purposes of the ACCA” is grounded in the Court’s decision in Wooden. Such interstitial rulemaking operates differently from the older style of common-law lawmaking through many decisions, and for some reason, rules like the rule of lenity only come about via the older style.

Finally, Justice Barrett’s opinion concurring in part and concurring in the judgment raises a somewhat related issue. She—joined by Thomas—agreed with the majority’s conclusion that the statute’s ordinary meaning was such that Wooden’s crimes occurred on a single occasion. She wrote separately simply to express disagreement with the majority’s use of legislative history as a further basis for its conclusion, stating that the “only thread connecting the occasions clause to Petty [the Eighth Circuit decision preceding enactment of the ‘occasions’ clause] is legislative history, and the problems with legislative history are well rehearsed.”

This point struck me as unnecessary (and part of a larger trend of the justices writing separately over what one might perceive as quibbles). The Court frequently employs one method of statutory interpretation in one case and a different method of statutory interpretation in the next. Surely, a purposivist like Justice Breyer can join a textualist opinion by Justice Scalia without worrying that his preferred interpretive approach will suddenly be off the table in the next case. Few would argue that the use of one method of interpretation over another in a given case has a precedential effect or even that use of one method in several cases has a precedential effect.

But that raises an intriguing question: Why does a string of cases employing the rule of lenity give rise to a legal norm (albeit one that is a bit indeterminate around the edges), while a string of cases employing a certain interpretive method does not? Or more concretely, why did Justice Scalia’s frequent appeals to textualism or originalism not make these methods part of our law? (To be clear, he didn’t claim that they were part of our law; rather, he consistently argued that courts ought to employ them for moral-political reasons.) This brings us back to Gorsuch and Kavanaugh’s dispute: How are judges to choose when to apply common-law closure rules like the rule of lenity rather than extralegal but conventionally accepted interpretive methods like purposivism, textualism, etc.? As of now, neither law nor practice provides an answer.