The Relationship Between The American Legal System and Non-domestic Law

Article VI, Paragraph 2 of the U.S. Constitution, often referred to as the Supremacy Clause, stipulates that “all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of ¬¬¬the land; and the judges in every state shall be bound thereby, anything in the Constitution or laws of any State to the contrary notwithstanding.” At first glance, the Supremacy Clause seems to specify that treaties are always self-executing – that is, integrated into U.S. law immediately upon signing and ratification. However, the relationship between non-domestic law – treaties, foreign laws, and international court judgments – and the American legal system is nuanced, more than what meets the eye. From Foster in 1829 to Medellin in 2008, Supreme Court cases have shaped the application of non-domestic law in the American legal system, solidifying the presumed self-executing nature of treaties and the role of foreign law in Court cases while limiting the binding authority of international court judgments.

Fourty-one years after the Constitution was ratified, the self-executing nature of treaties came into question in Foster v. Neilson, a case that revolved around ownership of a contested tract of land in Louisiana. In attempting to determine original ownership of the land, the Supreme Court of the United States (SCOTUS) examined the Adams-Onis Treaty of 1819 between Spain and the U.S. Because the eighth article of the treaty detailed that “all grants of land … shall be ratified and confirmed,” the Court concluded that the treaty was inherently non-self-executing, invalid without a subsequent act of Congress. However, the Court stressed that the non-self-executing nature of the Adams-Onis Treaty only arose because of the “ratified and confirmed” clause in its eighth article; treaties in general were still assumed to be self-executing unless otherwise spelled out in the text of the treaty. The majority wrote, “[Treaties are] regarded in courts of justice as equivalent to an act of the Legislature … But when the terms of the stipulation import a contract, when either of the parties engages to perform a particular act … the Legislature must execute the contract before it can become a rule for the Court.” Besides defining self-executing treaties as equal in authority to acts of Congress, the Court also set a precedent for some treaties, as well as other sources of international law, to be recognized as non-self-executing.

Even after SCOTUS specified that treaties could either be self-executing or non-self-executing, the relationships between treaties and the Constitution, federal laws, and state laws still remained ambiguous. In 1920, a treaty’s relationship to state law was questioned in Missouri v. Holland, where the state of Missouri argued against the constitutionality of a treaty between the United States and Great Britain that regulated the “killing, capturing, or selling” of “migratory birds” and conflicted with state law. Previously, the District Court had ruled against an earlier federal statute that regulated the killing of migratory birds. In this case, though, the Court decided that “a treaty may override [state] power” – hence, the Migratory Bird Treaty Act of 1918, a federal statute which applied the treaty, overrode Missouri state law regarding migratory birds. As the majority opinion explained, “By Article VI [of the Constitution] treaties made under the authority of the United States, along with the Constitution and laws of the United States made in pursuance thereof, are declared the supreme law of the land.”

Having established the supremacy of treaties above state law, the Court in 1957 further clarified the relationship between treaties, federal laws, and the Constitution, in Reid v. Covert. Executive agreements in effect between the United States and Great Britain and between the United States and Japan “permitted United States' military courts to exercise exclusive jurisdiction over offenses committed … by American servicemen or their dependents.” After being convicted of murder by overseas military tribunals, however, two military spouses alleged that American treaties could not override their Fifth and Sixth Amendment Constitutional protections. Eventually, the Court agreed, asserting that “no agreement with a foreign nation can confer power on the Congress, or on any other branch of Government, which is free from the restraints of the Constitution.” Furthermore, the Court established what is known today as the last-in-time rule: “An Act of Congress … is on a full parity with a treaty … when a statute which is subsequent in time is inconsistent with a treaty, the statute to the extent of conflict renders the treaty null.” Because federal laws are required to “comply with the Constitution,” and because treaties are on par with federal laws, treaties must therefore comply with the Constitution as well.

Unlike treaties, foreign law is not one of four sources of international law explicitly listed in Article 38 of the Statute of the International Court of Justice. Thus, the Supreme Court took an interesting turn in 2003, when it cited foreign law in favor of its own precedents. Lawrence v. Texas analyzed a Texan sodomy law that criminalized same-sex activity. The majority not only openly overturned Bowers, which had upheld the constitutionality of a Georgian sodomy law prohibiting oral and anal sex, but also cited laws from the British Parliament and other legislative bodies, along with a case from the European Court of Human Rights that had been decided five years prior to Bowers. The Court’s controversial deference to foreign law was unprecedented, given that previous decisions had only cited foreign law in footnotes, or perhaps dissents or concurrences. Moreover, the Court’s citations of foreign law did not seem particularly necessary; rather, by “voluntarily embracing international law as persuasive authority,” the Court seemed eager to “a poignant message to critics – who have seen the Supreme Court as insular – that the globalization trend does not end on the Supreme Court’s steps,” as Janet Koven Levit, J.D., pointed out.

While SCOTUS definitely set a precedent for using foreign law as a basis for the Court’s decision in Lawrence, it limited the authority of international case law in a case decided only five years later. Medellin v. Texas returned to the question of self-executing versus non-self-executing sources of international law, this time in regards to judgments from the International Court of Justice (ICJ). Medellin was a Mexican national who had unsuccessfully appealed his conviction on the grounds that Texan authorities had failed to notify him of his right to contact the Mexican consulate as prescribed in the Vienna Convention. However, the International Court of Justice had also ruled that Medellin, as well as fifty other Mexican citizens, were entitled to a review and reconsideration of their convictions and sentences. Quoting the United Nations Charter provision which detailed that “each Member of the United Nations undertakes to comply with the decision of the [ICJ] in any case to which it is a party,” the Supreme Court interpreted the phrase “undertakes to comply” as hinting at the non-self-executing nature of ICJ judgments. Additionally, the United States had previously withdrawn in 1985 from the Optional Protocol, which recognized “compulsory jurisdiction” of the ICJ regarding disputes related to the Vienna Convention. Even though “many Supreme Court cases [had found] treaty provisions to be self-executing,” the Court now seemed to reverse itself. Rather than assuming self-execution and searching for express language pointing to non-self-execution, the Court searched for express language indicating the self-executing nature of ICJ judgments. If ICJ judgments were indeed self-executing, the Court argued, then the United States’ Security Council veto would “would no longer be a viable alternative,” because “there would be nothing to veto.” Instead, the ICJ judgment merely constituted “an international law obligation” at most, as Justice Stevens declared in his concurring opinion. As a result, SCOTUS ruled that judgments from the ICJ were non-self-executing, concluding that “the pertinent international agreements, therefore, do not provide for implementation of ICJ judgments through direct enforcement in domestic courts.”

Even though the Constitution’s Supremacy Clause requires treaties to “be the supreme law of the land,” subsequent SCOTUS judgments have further allowed for non-self-executing treaties, which in time resulted in the non-self-executing nature of ICJ judgments. The cases examined, from Foster to Missouri to Reid to Lawrence to Medellin, have all tremendously shaped and defined the application of non-domestic law in the American legal system. Today, treaties are presumed to be self-executing American law unless otherwise excepted; foreign law can set precedents for American judicial law; international court judgments hold no binding authority on domestic law. Perhaps the majority opinion in Missouri best foresaw the re-definition and evolution of the Constitution when it declared, “We must realize that they have called into life a being the development of which could not have been foreseen completely by the most gifted of its begetters … The case before us must be considered in the light of our whole experience, and not merely in that of what was said a hundred years ago.”