Roberts, attempting to continue his vision of avoiding the Constitutional issue by rewriting a statute, cites Brandeis in Ashwander:

Notwithstanding this debate, it is “a well-established principle governing the prudent exercise of this Court’s jurisdiction that normally the Court will not decide a constitutional question if there is some other ground upon which to dispose of the case.” Escambia County v. Mc- Millan, 466 U. S. 48, 51 (1984) (per curiam); see also Ashwander v. TVA, 297 U. S. 288, 347 (1936) (Brandeis, J., concurring). Bond argues that section 229 does not cover her conduct. So we consider that argument first.

In his concurring opinion in Bond, Justice Scalia was livid at the Chief’s insistence, once again, to avoid the underlying merits, and decide the issue on some narrow statutory ground. The Chief spends most of his opinion explaining why Bond’s conduct should not be covered by the treaty, thus avoiding the constitutional issue:

As explained, the Convention’s drafters intended for it to be a compre- hensive ban on chemical weapons. But even with its broadly worded definitions, we have doubts that a treaty about chemical weapons has anything to do with Bond’s conduct. The Convention, a product of years of worldwide study, analysis, and multinational negotiation, arose in response to war crimes and acts of terrorism. See Kenyon & Feakes 6. There is no reason to think the sovereign nations that ratified the Convention were interested in anything like Bond’s common law assault.

The Chief, of course concludes:

This case is unusual, and our analysis is appropriately limited.

Justie Scalia is not persuaded:

Today, the Court shirks its job and performs Congress’s.

As sweeping and unsettling as the Chemical Weapons Convention Implementation Act of 1998 may be, it is clear beyond doubt that it covers what Bond did; and we have no authority to amend it. So we are forced to decide—there is no way around it—whether the Act’s application to what Bond did was

Scalia’s treatment of the majority’s analysis is brutal:

The Court does not think the interpretive exercise so simple. But that is only because its result-driven antitex- tualism befogs what is evident.

The Court’s account of the clear-statement rule reads like a really good lawyer’s brief for the wrong side, relying on cases that are so close to being on point that someone eager to reach the favored outcome might swallow them.

The same skillful use of oh-so-close-to-relevant cases characterizes the Court’s pro forma attempt to find ambi- guity in the text itself, specifically, in the term “[c]hemical weapon.” The ordinary meaning of weapon, the Court says, is an instrument of combat, and “no speaker in natu- ral parlance would describe Bond’s feud-driven act of spreading irritating chemicals on Haynes’s door knob and mailbox as ‘combat.’ ” Ante, at 15–16. Undoubtedly so, but undoubtedly beside the point, since the Act supplies its own definition of “chemical weapon,” which unquestiona- bly does bring Bond’s action within the statutory prohibi- tion. The Court retorts that “it is not unusual to consider the ordinary meaning of a defined term, particularly when there is dissonance between that ordinary meaning and the reach of the definition.” Ante, at 16. So close to true! What is “not unusual” is using the ordinary meaning of the term being defined for the purpose of resolving an ambiguity in the definition.  …

In this case, by contrast, the ordinary meaning of the term being defined is irrelevant, because the statute’s own definition—however expansive—is utterly clear: any “chemical which through its chemical action on life proc- esses can cause death, temporary incapacitation or per- manent harm to humans or animals,” §229F(8)(A), unless the chemical is possessed or used for a “peaceful purpose,” §229F(1)(A), (7)(A). The statute parses itself. There is no opinion of ours, and none written by any court or put forward by any commentator since Aristotle, which says, or even suggests, that “dissonance” between ordinary meaning and the unambiguous words of a definition is to be resolved in favor of ordinary meaning. If that were the case, there would hardly be any use in providing a defini- tion. No, the true rule is entirely clear: “When a statute includes an explicit definition, we must follow that defini- tion, even if it varies from that term’s ordinary meaning.” Stenberg v. Carhart, 530 U. S. 914, 942 (2000) (emphasis added). Once again, contemplate the judge-empowering consequences of the new interpretive rule the Court today announces: When there is “dissonance” between the statu- tory definition and the ordinary meaning of the defined word, the latter may prevail. 

To apply these presumptions, then, is not to rewrite clear text; it is to interpret words fairly, in light of their statutory context.

Who in the world would have thought that a defini- tion is inoperative if it contradicts ordinary meaning? When this statute was enacted, there was not yet a “Bond presumption” to that effect—though presumably Congress will have to take account of the Bond presumption in the future, perhaps by adding at the end of all its definitions that depart from ordinary connotation “and we really mean it.”