In his majority opinion, the Chief Justice declares that the Chemical Weapons Convention Implementation Act is ambiguous on whether it “reaches a purely local crime.” But rather than point to any relevant part of the Act that is fairly susceptible of more than one meaning, the Chief states that
the ambiguity derives from the improbably broad reach of the key statutory definition give the term—“chemical weapon”—being defined; the deeply serious consequences of adopting such a boundless reading; and the lack of any apparent need to do so in light of the context from which the statute arose—a treaty about chemical warfare and terrorism.
In his opinion concurring in the judgment, Scalia concludes that the “meaning of the Act is plain,” and he says that it is only the majority’s “result-driven antitextualism [that] befogs what is evident.” Scalia laments the “judge-empowering principle” that will find ambiguity in “[w]hatever has improbably broad, deeply serious, and apparently unnecessary consequences.” He complains, in particular, that the majority finds that “‘dissonance’ between ordinary meaning and the unambiguous words of a definition [‘chemical weapon’] is to be resolved in favor of ordinary meaning.” (Both Thomas and Alito join this part of Scalia’s opinion.)
Reaching the merits of the constitutional claim, Scalia would reject the dictum of Missouri v. Holland (1920) (any statute implementing a valid treaty is justified as a “necessary and proper means to execute the powers of the Government”) and would hold instead that Congress’s ability to implement treaties must derive from its ordinary Article I, section 8 powers. (Thomas also joins this part.)
In another opinion concurring in the judgment, Thomas (joined by Scalia and Alito) concludes that the Treaty Power “can be used to arrange intercourse with other nations, but not to regulate purely domestic affairs.”
I very much wish that the constitutional principles set forth in Scalia’s and Thomas’s opinions were the settled understanding of the Court.