Medellín v. Texas, 552 U.S. 491 (2008), was a decision of the United States Supreme Court that held even when a treaty constitutes an international commitment, it is not binding domestic law unless it has been implemented by an act of the U.S. Congress or contains language expressing that it is "self-executing" upon ratification.

The Optional Protocol provides that disputes arising out of the interpretation or application of the Vienna Convention "shall lie within the compulsory jurisdiction of the International Court of Justice.

[9] On June 24, 1993, José Ernesto Medellín, an 18-year-old Mexican citizen, and several other gang members participated in the murders of Jennifer Ertman and Elizabeth Peña, which involved their rape of a 14-year-old and 16-year-old girl for an hour in Houston, Texas.

Absent a clear and express statement to the contrary in either the Vienna Convention or the Optional Protocol, the Court held in Sanchez-Llamas that the procedural rules of each nation govern the implementation of the treaty.

[24] The ruling in Sanchez-Llamas did not control Medellín's case, however, since his claim was based on the rights accorded him as one of the individuals in the ICJ's judgment, rather than on the Vienna Convention.

The Court held that the Avena judgment is not enforceable as domestic law because unless Congress has enacted statutes implementing it or the treaty itself conveys an intention that it is "self-executing.

"[26] None of the relevant treaties – the Optional Protocol, the UN Charter, or the ICJ Statute – was self-executing, and no implementing legislation had been enacted, the Court found.

[27] The Court also rejected Medellín's claim that Article 94 of the UN Charter requires the United States to "undertake to comply" with the ICJ ruling.

Chief Justice Roberts observed that Article 94(2) of the Charter provides for explicit enforcement for noncompliance by referral to the UN Security Council, and for appeals to be made by only the aggrieved state, not an individual such as Medellín.

The Court relied on Youngstown Sheet & Tube Co. v. Sawyer, 343 U. S. 579 (1952), recognizing that "plainly compelling interests" were at stake in the Medellín case, but noted: Such considerations, however, do not allow us to set aside first principles.

The Court disagreed: "The President has an array of political and diplomatic means available to enforce international obligations, but unilaterally converting a non-self-executing treaty into a self-executing one is not among them.

"[35] All prior uses of executive authority to settle international disputes all occurred in narrow circumstances and did not involve the complete setting aside of state law, as the defendant sought in the present case.

[39] Breyer cited the 1796 case Ware v. Hylton, which he considered illustrative of what "the Founders meant when they wrote [in the Supremacy Clause of the United States Constitution] that 'all Treaties... shall be the supreme Law of the Land.'"

In Ware, the Supreme Court had agreed with a British creditor that a provision of the Treaty of Paris of 1783, which had been ratified by Congress, overruled a conflicting Virginia law.

Breyer noted that no further legislative act had implemented the treaty, but rather the Court found that its provisions were automatically incorporated as domestic law per the Supremacy Clause.

[40] Texas Governor Rick Perry rejected calls from Mexico and Washington, D.C., to delay the execution, citing the torture, rape and strangulation of two teenage girls as just cause for the death penalty.

[42] He notes that no justice challenged the Court's power and necessity to analyze even a presumably self-executing treaty, but rather disagreed on the proper analytical framework.