In pursuing the neutral application of the law, courts must discern the meaning of statutes. When a statute’s text is clear, courts apply that meaning. But what happens when a statute’s text is not clear? Courts have developed various tools and canons of interpretation that help resolve ambiguity in laws. Some of these canons are descriptive or linguistic, providing grammatical rules and clarifying speech patterns. Consider the negative-implication canon, which instructs that the expression of one thing implies the exclusion of others. A store advertisement that exclaims ‘Discounts for Veterans’ by necessity implies that non-veterans are not entitled to a discount. Or take the number canon, which explains that, in a legal text, the singular includes the plural and the plural includes the singular. In other words, an individual who defrauds a single person does not escape a law that prohibits the defrauding of people.
Such linguistic canons are relatively uncontroversial. Because their function is limited to giving full effect to the language adopted by legislators, linguistic canons pose no serious threat to the notion of legislative supremacy. These canons help judges discern the meaning of statutory language and faith and thus further courts’ general object of faithfully applying statutory text.
However, other interpretive rules advance principles outside of a statute. Such rules of construction are dubbed ‘substantive canons.’ When judges apply such canons, they illustrate the relationship between political principles and the interpretation of statutory language. Take the constitutional avoidance canon, which instructs that, if there are two plausible readings of a statute, but one raises constitutional concerns, courts ought to choose the interpretation that does not raise such a concern. An honest and impartial reading of statutory text can therefore be supplanted by overarching political values.
The legitimacy of substantive canons is thus much more contentious. Judges in nations like the United States are largely insulated from popular control. Indeed, the Enlightenment push for separation of powers and the establishment of judicial independence are hallmarks of modern liberal governance. So what then gives unelected judges the authority to override the ordinary meaning of statutory language in favour of external political values? The problem is still more pervasive. Even if we accept the legitimacy of substantive canons, courts lack clear criteria to decide when the application of substantive canons is warranted. Litigants and the public cannot reliably anticipate how genuine ambiguity in the law will be resolved, impairing the predictability that the rule of law demands.
Disputes over the application of substantive canons demonstrate how the emphasis placed on external, albeit constitutional, values can influence the meaning of the language of the law. As a representative example, consider the United States Supreme Court’s March 2024 decision in Pulsifer v. United States. This case concerned the interpretation of a federal law governing criminal sentencing and it asked the Court to consider the application of the rule of lenity, a principle that calls on courts to interpret ambiguous criminal laws in the manner most favourable to the defendant. Justice Elana Kagan, writing for the majority, applied a linguistic canon—the canon against superfluity, which urges courts to construe statutes to avoid redundancy. She concluded that the statute was not ‘genuinely ambiguous,’ thereby ‘leaving no role for lenity to play.’ But Justice Neil Gorsuch gave full effect to the rule of lenity in his dissenting opinion:
‘As I see it, the government hasn’t come close to supplying a lawful basis for departing from the law’s ordinary meaning. Suppose, though, at the end of this long march through its inventive theories you remain unsure. Suppose you are left with a reasonable doubt about whether Mr. Pulsifer or the government has the better reading of the law. In circumstances like that, another rule of construction supplies an answer. It is lenity.’
This opinion well illustrates the tension between linguistic canons and substantive canons. As Justice Gorsuch explained, the rule of lenity promotes important values: individual liberty, separation of powers, and due process rights ‘by ensuring individuals fair notice of the consequences of their actions.’ Justice Amy Coney Barrett has characterised the rule of lenity as ‘play[ing] the modest role of breaking a tie between equally plausible interpretations of a statute.’ But there are some substantive canons—’strong-form’ canons, to borrow Justice Barrett’s phrase—that encourage courts to strain text to advance external values. If substantive canons are not limited merely to breaking ties between similarly likely interpretations, courts would be permitted to adopt interpretations other than a reasonably likely one. This would raise much more serious separation-of-powers concerns.
Even if we accept that substantive canons are consistent with textualism, tough questions remain: How ambiguous must a statute be to trigger the application of a substantive canon? How plausible must an alternate reading of a statute be to make it permissible? These questions are of enormous consequence. For example, the very status of the Affordable Care Act, the landmark healthcare law in the United States, turned in significant part on the constitutional avoidance doctrine in NFIB v. Sebelius. There, to avoid the potential constitutional problems associated with mandating that individuals purchase health insurance, the Court interpreted the relevant provision as an exercise of Congress’s power to tax.
Questions of ambiguity are most prominent in cases involving the application of Chevron deference. Under Chevron, courts must defer to an administrative agency’s reasonable interpretation of an ambiguous statute. To warrant deference, a court must first determine whether a given statute is ambiguous. Justice Brett Kavanaugh has highlighted the problem inherent in determining what constitutes ambiguity, noting that judges lack a predictable method of deciding how much clarity is needed to deem a statute clear. To remedy the problem, Justice Kavanaugh has advocated that judges ‘strive to find the best reading of the statute’ and ‘stop using ambiguity as the trigger for applying these canons of statutory interpretation.’ That is a fine suggestion; it may well cure the problems of the ambiguity trigger under Chevron. It would not, however, help judges apply other substantive canons. If the most accurate reading of a statute raises constitutional concerns or provides for a more stringent criminal punishment, how plausible must an alternate reading of a statute be for a court to elect that interpretation? Is a very strained reading of an otherwise constitutionally problematic statute preferable to simply finding the statute unconstitutional? Though full application of the tools of statutory construction might cure the problems of administrative deference, courts would be left just as unguided as to when to apply substantive canons. The fate of litigants’ arguments would depend only on which particular canons any given judge tends to favour.
Ambiguity is a feature of language and statutory language is no exception. Language is context-dependent and reasonable people, and fair-minded jurists, may interpret identical language in distinct ways. On a broader level, the issues surrounding substantive canons raise serious questions about political values. The legitimacy of substantive canons turns in part on our willingness to allow judges to apply external political values to statutory text. Do we trust judges to enforce federalism, due process, and other important political goals by elevating those values above the ordinary meaning of language? The move in American courts towards textualism over the last few decades has played an important role in constraining the ability of judges to implement their own personal policy preferences . Judges are bound by text and are not free to import their own personal values into the law. But textualists must still grapple with—and provide a philosophical justification for—the fact that substantive canons allow judges to elevate external political values over the plain meaning of a legal text. Even if substantive canons are legitimate, lower courts require—somewhat ironically—clarity from the Supreme Court to help them determine where there exists enough ambiguity to trigger those interpretative rules.
This article was originally published in OPR’s Issue 13: Language.
Arpit Rao is a third-year Economics and Government Student at Dartmouth College in the United States.