David Sloss’s article, Executing Foster v. Neilson, is an important contribution to the literature on the judicial enforcement of treaties. I agree with much of it, as I agree with much of Professor Sloss’ other writing on treaties. In particular, I agree that the two-step approach to treaty enforcement that he proposes is generally the right approach, and I agree that the “intent-based” approach to the self-execution issue that he criticizes is highly problematic. But Professor Sloss and I disagree about the source of this problematic approach. I have traced this approach to Chief Justice Marshall’s opinion in Foster v. Neilson. Professor Sloss traces it to courts and scholars (including me) who, in his view, have misread Foster. I shall address our differences on this point below. First, however, I shall explain my general agreement with the two-step approach to treaty enforcement that Professor Sloss defends.
The much-controverted question of treaty self-execution is widely understood to concern whether a treaty may be enforced directly by the courts or must instead await legislative implementation. Professor Sloss proposes a two-step analysis for addressing this question. The first step is to determine what the treaty obligates the United States to do. This is a question of treaty interpretation, to be answered through the application of the international law of treaty interpretation. The second step is to identify which domestic officials have the power and duty to enforce the obligation. This, Professor Sloss argues, is entirely a matter of U.S. domestic law, not a matter of treaty interpretation. Courts and commentators have fallen into error, and produced much confusion, by treating the second question as one of treaty interpretation, seeking an answer in the text of the treaty or in the parties’ intent. Professor Sloss notes that treaties seldom address the question of which domestic officials—legislative, executive, or judicial—are responsible for enforcing the treaty. Instead, treaty parties almost always leave that question to the domestic law of the states-parties.
Professor Sloss is entirely correct to note that seeking the answer to this question in the treaty itself is highly problematic. Although there is nothing in international law that prevents states from addressing that question in the treaty itself, the fact is that states almost never do so. Domestic officials take their cues from domestic law, and states have very different constitutional rules concerning the need for legislative implementation of treaties. In the United Kingdom and most nations of the British Commonwealth, treaties are never enforceable in the courts until they have been implemented by legislation. The constitutional law of other countries permits the direct judicial enforcement of some treaties but not of others. In the United States, for example, treaties that require the criminalization of conduct or the appropriation of money must be legislatively implemented because the Constitution has been interpreted to require a statute for those purposes. Because of the diversity of domestic constitutional rules on the question, states rarely, if ever, address the issue of domestic implementation in the treaties they conclude. Seeking an answer to the self-executing question in the treaty itself is thus, in Justice Breyer’s words, like “hunting [for] the snark.”No matter how hard they look, the courts will almost never find an answer there.
 David L. Sloss, Executing Foster v. Neilson: The Two-Step Approach to Analyzing Self-Executing Treaties, 53 Harv. Int’l L.J. 135 (2012).
 See, e.g., David L. Sloss, Self-Executing Treaties and Domestic Judicial Remedies, 98 Am. Soc’y Int’l L. Proc. 364 (2004); David L. Sloss, Non-Self-Executing Treaties: Exposing a Constitutional Fallacy, 36 U.C. Davis L. Rev. 1 (2002); David L. Sloss, The Domestication of International Human Rights: Non-Self-Executing Declarations and Human Rights Treaties, 24 Yale J. Int’l L. 129 (1999).
 Sloss, supra note 1, at 163.
 Carlos Manuel Vázquez, Treaties as Law of the Land: The Supremacy Clause and the Judicial Enforcement of Treaties, 122 Harv. L. Rev. 599, 607 (2008) [hereinafter Vázquez, Treaties as Law]; Carlos Manuel Vázquez, The Four Doctrines of Self-Executing Treaties, 89 Am. J. Int’l L. 695, 700–05 (1995) [hereinafter Vázquez, Four Doctrines]; Carlos M. Vázquez, Foster v. Neilson and United States v. Percheman: Judicial Enforcement of Treaties, in John E. Noyes et al., International Law Stories 151, 167–68 (2007) [hereinafter Vázquez, International Law Stories]; Foster v. Neilson, 27 U.S. (2 Pet.) 253 (1829).
 Sloss, supra note 1, at n.26 (citing Vázquez, Treaties as Law); Curtis A. Bradley, Self-Execution and Treaty Duality, 2008 Sup. Ct. Rev. 131; Ernest A. Young, Treaties as “Part of Our Law,” 88 Tex. L. Rev. 91 (2009).
 See Sloss, supra note 1, at 137.
 Id. at 143.
 Id. at 137–40, 143, 162, 188.
 See generally id.; see, e.g., Medellín v. Texas, 552 U.S. 491, 504–05 (2008).
 Sloss, supra note 1, at 163.
 Vázquez, Treaties as Law, supra note 4, at 607.
 Id. at 679; Duncan B. Blakeslee et al., National Treaty Law and Practice 733–34 (2005).
 Id. at 17–18.
 Restatement (Third) of the Foreign Relations Law of the United States § 111(4)(c) cmt.i, n.6 (1987).
 Medellín, 552 U.S. at 549 (Breyer, J., dissenting).