Today’s Supreme Court decision in Bond v. United States largely avoids the big constitutional issue that was the original focus of the case: the scope of the treaty power. Carol Anne Bond had been prosecuted by the federal government for violating 18 U.S.C. Section 229, the federal statute implementing the Chemical Weapons Convention, which bans the use of “chemical weapons.” Bond had tried to use toxic substances to harm another woman who had been having an affair with Bond’s husband, by coating her mailbox and doorknob with them.

The implementing statute bans the use and possession of all “chemical weapons” and very broadly defines that category to include any “toxic chemical and its precursors, except where intended for a purpose not prohibited under this chapter as long as the type and quantity is consistent with such a purpose.” The excepted purposes are “[a]ny peaceful purpose related to an industrial, agricultural, research, medical, or pharmaceutical activity or other activity.” Despite this extremely broad language, the Court avoided the issue of whether the law falls within the scope of the treaty power by concluding that Section 229 does not actually ban what Bond did. This enables the Court to avoid the difficult treaty power issue: whether treaties can authorize Congress to legislate beyond the scope of its other enumerated powers.

But the Court’s opinion still has at least some implications for the treaty power question. In order to interpret Section 229 to exclude Bond’s conduct, Chief Justice John Roberts’ majority opinion (joined by six justices in all) applied the longstanding canon against construing federal laws as upsetting “the usual constitutional balance of federal and state powers” unless the law does so very clearly. In this case, the Court concluded that it was plausibly possible to interpret the law narrowly so as to avoid intruding into “local” criminal conduct, such as what Bond did. Notice, however, that Section 229 would not upset “usual constitutional balance” between the states and the federal government if the latter has a power to sign and implement treaties regardless of their subject matter. In that event, a treaty covering “local” conduct would be just constitutional business as usual.

Therefore the majority opinion at least suggests that there are serious doubts about whether the treaty power can reach local crimes like those committed by Bond. That doesn’t mean that the majority justices clearly conclude that it does not reach it. They did ultimately avoid that issue, after all. But it at least hints in that direction.

Justice Scalia’s concurring opinion (joined on this point by Thomas and Alito), rejects the majority’s interpretation of Section 229. Rightly so, in my view. As Scalia emphasizes, Section 229 seems both clear and broad, forbidding all use and possession of “toxic substances” unless for a “peaceful purpose.” Bond pretty obviously used and possessed toxic substances, and equally obviously, her use was not peaceful.

Scalia, joined by Thomas, also concludes that the treaty power does not give Congress the authority to enact implementing statutes that go beyond the scope of Congress’ other enumerated powers under Article I. In a separate concurring opinion, Justice Thomas, joined by Scalia and Alito, argues that Section 229 is unconstitutional because the the treaty power only extends to treaties addressing “matters of international intercourse,” but does not cover “matters of purely domestic regulation” such as Bond’s conduct.

I agree with Scalia and Thomas that Section 229 is beyond the scope of the treaty power. But I am not fully satisfied by the reasoning of either. Scalia’s argument implies that the federal government has the power to sign treaties on a broader range of issues than Congress can legislate to implement. As he puts it, the “power to help the President make treaties is not a power to implement treaties already made.” The latter does not extent to treaties outside the scope of Congress’ enumerated powers. In my view, outlined in more detail here, a a constitutionally valid treaty can only cover subjects that are within scope of preexisting federal power to begin with. A treaty is a contract between national governments. As Federalist 64 puts it, “a treaty is only another name for a bargain.” Just as a valid contract between individuals can only cover such issues as those individuals have a preexisting right to decide, so a treaty between national governments can only address issues within the scope of those government’s powers. Thus, a treaty that goes beyond the scope of Congress’ preexisting authority is invalid to begin with, not simply a possibly valid treaty that Congress lacks the authority to implement.

I also have some issues with Thomas’ position. His theory implies that the federal government cannot sign treaties on matters within the scope of Congress’ Article I powers, if the issue in question is not a “matter of international intercourse.” As Thomas recognizes, that’s a very vague standard. But it is also wrong because there is no constitutional problem with a treaty that covers a “non-international” matter within the scope of congressional power. Just as I can sign a private contract committing myself on an issue that would normally be considered purely personal, so a government can sign a treaty committing itself on an issue that would normally be considered purely local, so long as the government has the authority to legislate on that issue.

Be that as it may, today’s decision does not ultimately resolve the issue of the scope of the treaty power. But it does suggest that all nine justices have at least some qualms about the notion – advanced by the federal government and many academics – that there are no structural limits to the scope of that power.

Interested readers may wish to check out last year’s VC debate on the scope of the treaty power between Rick Pildes, co-bloggers Nick Rosenkranz and Eugene Kontorovich, and myself. All the posts were reprinted by the Green Bag.

UPDATE: It is worth noting that this is one of the few cases that has gone to the Supreme Court twice. Even more unusually, Carol Anne Bond prevailed both times without losing a single justice’s vote. I wrote about the Court’s previous Bond decision (where it reached the important conclusion that individuals can raise Tenth Amendment issues about the limits of federal power) here.

UPDATE #2: I have edited my discussion of Scalia’s opinion to take account of the fact that he also joined Thomas’ opinion. I apologize for not sufficiently considering this point in the original version of this post. Because the edit was made only about 45 minutes after initial posting, I am not going to go over the changes in detail.

UPDATE #3: I should briefly mention Justice Alito’s concurring opinion, which mostly endorses points made in Scalia and Thomas’ opinions, but does also indicate that “the heart” of the Chemical Weapons Convention is constitutional, since the control of chemical weapons is “clearly a matter of great international concern.”