Curtis Bradley (University of Chicago Law School) has posted International Agreements by U.S. States: Federalism, Foreign Affairs, and Constitutional Change (40 pages) on SSRN. Here is the abstract:
The text of the U.S. Constitution appears to require that, to the extent that individual states are ever allowed to conclude agreements with foreign governments, they must obtain congressional approval. In practice, however, states conclude many agreements with foreign governments and almost never seek congressional approval. This practice is an illustration of both the importance of federalism in U.S. foreign relations and the significant role played by historical practice in informing U.S. constitutional interpretation. The phenomenon of state international agreements assumed new prominence in 2019 when the Trump administration sued to challenge a climate change agreement that the state of California had made with the Canadian province of Quebec. Despite this challenge, for the most part neither Congress nor the executive branch has resisted the growth in state international agreements. This acquiescence could change as countries like China target U.S. states in an effort to work around strained relations with the U.S. national government, and as states become more assertive in resisting the national government’s foreign policies. In any event, the practice of state international agreements unapproved by Congress rests in part on a distinction between binding and nonbinding agreements that deserves greater scrutiny under both domestic and international law.
(Via Larry Solum at Legal Theory Blog, who says "Highly recommended.")
There is isn't a good originalist account of this issue, and I haven't looked at it closely enough to have definite views, but I think the suggestion that many of these "agreements" are actually nonbinding is a helpful one. (Calling an agreement nonbinding solves a lot of constitutional issues: see my thoughts here). It may also be, though, that we have just ended up very far from the original meaning for no good reason.
Posted at 6:02 AM