The Treaty Paradox

[Emsworth]

The Slave Trade Clause, by its own terms, applies only to Congress. The clause does not, therefore, restrict the President's treaty-making power. Nevertheless, I would hold that a treaty purporting to prohibit individuals from engaging in the slave trade would be unconstitutional, or at the very least non-self-executing.

The power to "regulate Commerce with foreign Nations" is expressly vested in Congress by Art. I, Sec. 8, Cl. 3. Furthermore, the regulation of international commerce is very clearly a "legislative power," and "all legislative powers" are vested in Congress by Art. I, Sec. 1. I would argue that, if a power is vested in Congress, then the President may not exercise that same power, by ratifying a treaty or otherwise. Thus, a treaty may not prohibit the slave trade (since such a prohibition is a regulation of international commerce).

Whether any treaty at all can be self-executing is a very difficult question. The answer is not immediately clear from the text of the Constitution. I'll try to make another post on the subject sometime soon.

[Emsworth]

The SC state legislature found that a freeborn citizen of an allied nation could not be subject the "Negro Laws" even if they happened to be black.

How is this law relevant to my claim that the treaty-making power cannot overlap with the legislative power of Congress?

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Treaties are not on a "level equal to the Constitution." The Constitution expressly provides for a few methods of amendment, and treaty-making is not one of them. Furthermore, under the supremacy clause, treaties are only the supreme law of the land if they are made under the "authority" of the United States. That authority has only one source: the Constitution itself. Thus, treaties are, just like acts of Congress, subject to constitutional restrictions.

[Emsworth]

It show that a state legislature, one that, a few years later, was willing to nullify federal statute, would recognize the primacy of a treaty between the US and foreign power.

I definitely agree that a treaty supersedes state law. There is no need to cite historical events; the text of the Constitution is clear enough to resolve the issue. Under the supremacy clause, treaties made under the authority of the United States are the supreme law of the land, any state law to the contrary notwithstanding.

But this discussion is not about whether valid treaties trump state law. The dispute is about whether a particular treaty--a treaty purporting to abolish the slave trade--is valid in the first place. If it is valid, then state laws to the contrary are void, but it must first be established that the treaty is constitutional.

Clearly, there must be some limits to the treaty power, beyond the requirement that the Senate advise and consent by a two-thirds majority. Could a treaty impose taxes, or regulate the jurisdiction of the Supreme Court, or appropriate funds from the Treasury? I would think not. The power to abolish the slave trade, and the power to regulate international commerce more generally, is of the same ilk -- it is delegated to Congress, not the President.

[Emsworth]

In the first place, it is somewhat odd to suppose that a treaty may do only and precisely those things that are placed beyond the reach of Congress by the enumerated powers scheme.

That's not what I said. If a power is delegated to Congress, the President may not exercise it. As Cyrus King, congressman from Massachusetts, explained in 1815:

"[W]henever a treaty or convention does, by any of its provisions, encroach upon any of the enumerated powers vested by the Constitution in the Congress of the United States ... such treaty or convention, after being ratified, must be laid before Congress, and such provisions cannot be carried into effect without an act of Congress. For instance, whenever a treaty affected duties on imports, ... whenever a treaty went to regulate commerce with foreign nations, ... as the power to lay duties and the power to regulate commerce are expressly given to Congress, such provisions of such treaty must receive the sanction of Congress before they can be considered as obligatory and as part of the municipal law of this country."

However, the inverse of this rule is not true. Just because a power is not delegated to Congress, it does not follow that it must belong to the President. In other words, the non-inclusion of a power among the powers of Congress is a necessary condition for the exercise of that power by treaty; it is not a sufficient condition.

[Emsworth]

I think that at least one further limit on the treaty power is implicit in the Constitution: the treaty must affect, relate to, or concern the foreign sovereign with whom it is made. The United States may not make a (self-executing) treaty establishing a purely domestic rule, even if other countries agree to adopt the rule at the same time. Thus, for example, an international convention forbidding all child executions could not be self-executing.