Which supersedes the other, laws or treaties?
<p>The <a href="https://en.wikipedia.org/wiki/Supremacy_Clause" rel="nofollow noreferrer">Supremacy Clause</a> of the U.S. Constitution states that the Constitution, laws and treaties are the supreme law of the land. Obviously, the Constitution supersedes both laws and treaties, but which is given more importance, laws or treaties? For example, if the Congress passed a law in violation of a treaty, would that law be valid? If the Senate ratified a treaty in violation of federal law, would that treaty be valid?</p>

<p>The U.S. law rule is that treaties and laws are co-equal and that one does not supersede the other. In the U.S., the rule is that the last passed law or treaty prevails, over earlier passed laws or treaties if they conflict. <em>See, e.g.</em>, Julian G. Ku, "<a href="https://www.repository.law.indiana.edu/cgi/viewcontent.cgi?article=1538&amp;context=ilj" rel="nofollow noreferrer">Treaties as laws: A Defense of the Last-in-Time Rule for Treaties and Federal Statutes</a>" 80 Indiana Law Journal 319 (2005) citing cases including <em><a href="https://supreme.justia.com/cases/federal/us/124/190/" rel="nofollow noreferrer">Whitney v. Robertson</a></em>, 124 U.S. 190 (1888).</p>

<p>But, this is not self-evident, Indeed, it is a minority rule of law to the point of pretty much being an outlier. In the vast majority of countries other than the U.S., domestic laws are subordinate to treaties, and there is some hint in the structure of the U.S. Constitution and the discussions of the Founders regarding the treaty power, that this how the Founders assumed that conflicts between treaties and domestic statutes would be interpreted, even though the U.S. Supreme Court ended up interpreting the constitution differently. Few countries in the world give so little legal effect to international treaties and international law, more generally, as the U.S. does. In contrast, in Europe, many human rights protections arise from international treaty obligations that override domestic laws, rather than from their own domestic constitutional law.</p>

<p>Also, while this rule seems simple and mechanical, it rarely presents in the fashion, because there are a variety of tools, such as interpreting treaties and statutes in a manner that avoids a conflict (particularly with respect to questions such as whether a treaty should be considered "self-executing" or not, and a rule of construction that one enactment that does not expressly overrule another should not be deemed to do so implicitly unless there is no interpretation that can resolve the conflict otherwise), that muddy the waters. As Ku, explains in the law review article linked above:</p>

<blockquote>
  <p>Although the Constitution declares that treaties are the "supreme Law
  of the Land,"the status of treaties in the American legal system is
  plagued by uncertainty. A court considering a private individual's
  claim under a treaty must first consider a number of complex questions
  such as whether the treaty is "self-executing," whether the treaty's
  effect is otherwise nullified by conditions placed on it during
  ratification, whether the treaty exceeds constitutional limitations on
  the exercise of the treaty power, and whether the treaty conflicts
  with inconsistent federal and state law.... For instance, in recent years 
  the International Court of Justice ("ICJ") has twice found that U.S.
  domestic law limiting habeas corpus appeals violated U.S. treaty
  obligations to guarantee consular notification rights to foreign
  nationals charged with capital crimes.' The ICJ found a conflict
  between the treaty and U.S. law even though the U.S. government
  offered a plausible alternative interpretation of the treaty that
  avoided conflict with domestic law.</p>
</blockquote>

<p>(Despite these findings, the U.S. did not enforce the alleged treaty obligation.)</p>

<p>A good example of this is the case of <em><a href="https://www.law.cornell.edu/supremecourt/text/12-158" rel="nofollow noreferrer">Bond v. United States</a></em>, 572 U.S. ___ (2014) (note that it is important to provide a year when discussing the <em>Bond</em> case, because the U.S. Supreme Court made two successive rulings in this case and also established an important precedent in an unrelated case with the same name). Wikipedia's summary of the case explains how the case avoided having to resolve constitutional issues in the case (references to <em>Holland</em> are to <em>State of Missouri v. Holland</em>, linked and discussed below):</p>

<blockquote>
  <p>Carol Anne Bond is a microbiologist from Lansdale, Pennsylvania. In
  2006, her best friend became pregnant. When Bond discovered that her
  husband was the child's father, she attempted to poison her former
  friend by putting organoarsenic and potassium dichromate on the
  woman's door knob. Bond was caught, and was convicted under the Chemical Weapons Act.
  In her appeal, she argued that applying the chemical weapons treaty to
  her had violated the Tenth Amendment. The Court of Appeals ruled that
  Bond lacked standing to make a Tenth Amendment claim. On appeal, the
  Supreme Court reversed by stating that individuals can bring Tenth
  Amendment claims. The Court then remanded the case for the Third
  Circuit to decide the case on the merits.</p>
  
  <p>On remand, the Third Circuit found that "because the Convention is an
  international agreement with a subject matter that lies at the core of
  the Treaty Power and because <em>Holland</em> instructs that 'there can be no
  dispute about the validity of [a] statute' that implements a valid
  treaty, we will affirm Bond's conviction." Bond again appealed to the
  Supreme Court, asking the court to overrule <em>Holland</em> or to find that
  her actions were not covered by the CWA.</p>
  
  <p>The case attracted a great deal of attention, with US Solicitor
  General Donald Verrilli arguing for the government and former
  Solicitor General Paul Clement arguing for Bond. Senator Ted Cruz
  wrote an essay for the blog of the Harvard Law Review, urging the
  Court to overturn Bond's conviction.</p>
  
  <p>Chief Justice Roberts opened his opinion by vividly describing John
  Singer Sargent's life-sized painting of mustard gas victims. Roberts
  closed by noting, "There are no life-sized paintings of Bond's rival
  washing her thumb."</p>
  
  <p>In its judgment, the Court unanimously concluded that the convention
  was not meant to cover local activities such as Bond's poisoning
  attempt. Writing for the Court, Chief Justice Roberts declined to
  define the scope of Treaty Clause powers, invoking constitutional
  avoidance. Because the Chemical Weapons Convention is not
  self-executing and because it requires implementation by a signatory
  to be "in accordance with its constitutional processes," Roberts
  focused his attention on statutory interpretation of the federal
  criminal code.</p>
  
  <p>According to Roberts, one of the key "background principles of
  construction" is federalism; there must be a "clear indication" by
  Congress if it intends to "dramatically intrude upon traditional state
  criminal jurisdiction." The Court concluded that there was no such
  clear indication in the text of the criminal statute.</p>
  
  <p>Roberts rejected the Solicitor General's interpretation of the
  statute, noting that the government's reading would make it a federal
  offense to poison children's goldfish and that state authorities are
  fully capable of punishing burrito poisoners.</p>
  
  <p>Finally, Roberts briefly responds to Justice Scalia's interpretation
  by noting that adopting "the most sweeping reading of the statute
  would fundamentally upset the Constitution's balance."</p>
  
  <p>A well-known line from his opinion is at the end: "The global need to
  prevent chemical warfare does not require the Federal Government to
  reach into the kitchen cupboard, or to treat a local assault with a
  chemical irritant as the deployment of a chemical weapon."</p>
</blockquote>

<p>Thus, rather than ruling that a law implementing a valid treaty was unconstitutional, the U.S. Supreme Court interpreted the law implementing the treaty in a manner that did not mean something that would potentially make the law unconstitutional.</p>

<p>The question states:</p>

<blockquote>
  <p>Obviously, the Constitution supersedes both laws and treaties</p>
</blockquote>

<p>This is mostly correct under U.S. law (although it took many decades before that rule was established in precedent), but it was not obvious under U.S. law, it is not true in every country, and it is not entirely settled law in the U.S. even today.</p>

<p>A plurality of the justices <em><a href="https://supreme.justia.com/cases/federal/us/354/1/" rel="nofollow noreferrer">Reid v. Covert</a></em>, 354 U.S. 1 (1957), which enforced the Fifth and Sixth Amendments against a contradictory treaty, stated: </p>

<blockquote>
  <p>There is nothing in this language which intimates that treaties and
  laws enacted pursuant to them do not have to comply with the
  provisions of the Constitution.</p>
</blockquote>

<p>A plurality decision, however, is not controlling authority that must be followed by lower courts.</p>

<p>But, in <em><a href="https://supreme.justia.com/cases/federal/us/252/416/" rel="nofollow noreferrer">State of Missouri v. Holland</em></a>, 252 U.S. 416 (1920) had previously reached an arguably contrary conclusion. The official syllabus to that decision noted that:</p>

<blockquote>
  <p>Protection of its quasi-sovereign right to regulate the taking of game
  is a sufficient jurisdictional basis, apart from any pecuniary
  interest, for a bill by a State to enjoin enforcement of federal
  regulations over the subject alleged to be unconstitutional.</p>
  
  <p>The Treaty of August 16, 1916, 39 Stat. 1702, with Great Britain,
  providing for the protection, by close seasons and in other ways, of
  migratory birds in the United States and Canada, and binding each
  power to take and propose to their lawmaking bodies the necessary
  measures for carrying it out, is within the treaty-making power
  conferred by Art. II, § 2, of the Constitution; the Act of July 3,
  1918, c. 128, 40 Stat. 755, which prohibits the killing, capturing or
  selling any of the migratory birds included in the terms of the
  treaty, except as permitted by regulations compatible with those terms
  to be made by the Secretary of Agriculture, is valid under Art. I, §
  8, of the Constitution, as a necessary and proper means of
  effectuating the treaty, and the treaty and statute, by bringing such
  birds within the paramount protection and regulation of the Government
  do not infringe property rights or sovereign powers respecting such
  birds reserved to the States by the Tenth Amendment. <strong>With respect to
  right reserved to the State, the treaty-making power is not limited to
  what may be done by an unaided act of Congress.</strong></p>
</blockquote>

<p>Many legal scholars expected that <em>Bond</em> (2014) would resolve the tension between <em>Reid</em> and <em>Holland</em>, but instead, the U.S. Supreme Court punted, and declined to reach that issue in that case.</p>

<p>Arguably, <em>Reid</em> and <em>Holland</em> are not truly in conflict, because <em>Holland</em> addresses the scope of the treaty power in light of federalism concerns, which isn't necessarily identical to the scope power of Congress to enact domestic laws pursuant to U.S. Constitution, Article I, Section 8 in light of federalism concerns, while <em>Reid</em> concerns constitutional provisions which have been interpreted to flatly prohibit the government from abridging certain individual rights at all. U.S. Constitution Article I, Section 8 limits the authority of Congress to enact domestic laws to certain enumerated subjects (with all other powers reserved to the states), while the treaty power is not limited to any particular subject-matter (in part, because states are not permitted under the constitution to enter into international treaties, so the federal government needs to handle treaties involving both national and state level concerns, while states have plenary power to enact domestic laws in all circumstances where they are not expressly prohibited from doing so).</p>

united-states constitutional-law us-constitution treaty