Justice Scalia and Bryan Garner’s fifth fundamental principle—“An interpretation that validates outweighs one that invalidates”—may usefully be considered in conjunction with the canon that a “statute should be interpreted in a way that avoids placing its constitutionality in doubt.”
The presumption-of-validity principle “disfavors interpretations that would nullify [a] provision or the entire instrument” (and, like the other fundamental principles, applies to all legal texts, whether private, e.g., wills and contracts, or public, e.g., statutes). The constitutional-doubt canon is not simply a particular application of this general presumption. Rather, it “goes much further” and “militates against not only those interpretations that would render the statute unconstitutional but also those that would even raise serious questions of constitutionality.” Where a statute is “susceptible” of an alternative interpretation that doesn’t raise a serious question of constitutionality, the canon operates to favor that alternative interpretation.
What threshold must be passed in order for an interpretation to raise a “serious” (or “grave” or “doubtful”) question of constitutionality and thus to trigger the canon? Alas, this question “cannot be precisely answered in the abstract.” Ditto, it would seem from the Supreme Court’s recent Obamacare ruling, for the separate question what it means for a statute to be “susceptible” of an alternative, constitutionally unproblematic interpretation (or, otherwise stated, whether that alternative interpretation is “fairly possible”). There is therefore room for a lot of disagreement in particular cases on whether the constitutional-doubt canon should apply.
One other observation on the Obamacare ruling: As I see it, the distinction that Scalia and Garner draw between the presumption-of-validity principle and the constitutional-doubt canon would (if accepted, of course) bolster Justice Ginsburg’s criticism (slip op. at 37 & n. 12) that the Chief Justice shouldn’t have gone so far as to conclude that the individual mandate couldn’t be justified under Congress’s Commerce Clause power. Specifically, if the Chief Justice had applied the constitutional-doubt canon as Scalia and Garner elaborate it, he arguably would have gone no further than to opine that the minimum-coverage provision, read as a mandate-with-penalty, raises serious questions as to its constitutionality, and he would have instead then resorted to the alternative interpretation of the provision as a tax (an interpretation that he, unlike Scalia and the other dissenters, regarded as “fairly possible”).