1. Mexican Judges as Protectors of the Rights and Duties of Private Persons under International Law

As mentioned earlier, the vertical norms of international law have granted rights and duties to private persons, which can be invoked in domestic proceedings before national judges. There are several areas in which international law grants direct rights and duties to individuals. Many international norms and principles, applicable at the regional and universal level, protect the rights of some categories of individuals (refugees, stateless persons or workers) and the human rights of all private persons. Additionally, some regional human rights courts (like the European Court of Human Rights) have considered companies to enjoy a limited number of human rights. Private persons can invoke their human rights before international bodies (some UN bodies are competent in human rights protection) and before specialized regional courts and tribunals (like the European Court of Human Rights, the Inter-American Court of Human Rights or the African Court of Human Rights). All international human rights instruments establish the exhaustion of local remedies as a prerequisite for international judicial protection. Thus the ordinary, and primary, responsibility to protect international human rights belongs to national judges.

As noted, Mexican judges are increasingly acting as “ordinary judges of international human rights law”. They have actively assumed a new role as “inter-American judges”.¹⁷ In a growing number of cases, Mexican judges have afforded individuals judicial protection of their human rights, granted directly by international treaties.

Since 2008, circuit courts have considered that individuals can invoke human rights provisions contained in international treaties in constitutional protection lawsuit (amparo) proceedings.¹⁸ In other words, the circuit courts recognized that Mexican judges have jurisdiction over disputes related to the violations of human rights. This is recognized not only in the Mexican Constitution, but also in international human rights treaties.

In a 2007 case, the Supreme Court guaranteed the freedom of expression and the prohibition of censorship, in accordance with Article 7 of the Mexican Constitution and Article 13 of the American Convention on Human Rights.¹⁹ The Court mentioned that freedom of expression can’t be restricted without the approval of competent authorities and that this freedom is co-substantial to the rule of law and democracy. In a case decided in 2008, the Supreme Court extended the scope of the judicial protection of the right to health, pursuant to Article 25 of the Universal Declaration of Human Rights, Article 12 of the International Pact on Economic, Social and Cultural Rights and Article 10 of the Additional Protocol of the American Convention on Human Rights on Social, Economic and Cultural Rights (which is also called the San Salvador Protocol). In 2008, Mexico’s Supreme Court clarified the meaning of the right to respect of private life, enounced in Article 12 of the Universal Declaration of Human Rights, Article 17 of the International Pact on Social and Political Rights, Article 11 of the American Convention on Human Rights and Article 16 of the Convention on the Rights of the Child.²⁰ The Supreme Court emphasized that the right to health, in conformity with these international law instruments, includes the access to a wide range of facilities, goods and services, as well as access to all other conditions necessary to enjoy a state of optimum health.²¹ In 2000, the Supreme Court protected the right to life, by virtue of the provisions of the Convention on the Rights of the Child and the International Pact on Civil and Political Rights.²² In an interesting case, resolved in 2011, a circuit court assumed possible violations to the right to honor, even if it is not granted by the Mexican Constitution. The court considered itself competent to afford protection regarding the right to honor, based solely on the provisions of the American Convention on Human Rights and the International Pact on Civil and Political Rights.²³

In other cases, Mexican judges have been activists regarding the recognition of individual rights as human rights in international law. In the Florence Cassez case,²⁴ the Mexican Supreme Court took a position on the ongoing controversy surrounding the acceptance of the right to information on consular assistance as a human right. This is established in Article 36 of the Vienna Convention on Consular Relations. In accordance with the Advisory Opinion of the Inter-American Court of Human Rights OC-16/99²⁵ and in dissonance with the Avena case²⁶ of the International Court of Justice, the Mexican Supreme Court considered that Article 36 grants this human right to individuals. In a clear performance of an international judicial function, Mexico’s Supreme Court considered “the right to notification, contact and consular assistance as an encounter point of two basic international law requirements. In the first place, the strengthening of the position of consular offices as representative of the sovereignty of the sending State and, on the other hand, the respect for human rights and the importance of their effective judicial protection, as an element of the due process of law.”²⁷ The Supreme Court then ordered the liberation of Florence Cassez, a French citizen, arrested in violation of her right to information on consular assistance, without dismissing the criminal claims against her.

These recent cases show the willingness of Mexican judges to afford judicial protection of individual human rights under international law. In almost all ongoing cases in which Mexican judges deal with human rights violations, they have recourse not only to a constitutional basis in domestic law, but also, complementary or exclusively, to a basis in international human rights treaties. This evolution has significantly strengthened individual human rights protection in the Mexican legal order, and has paved the way towards a growing acceptance of the performance of an international (human rights) judicial function by Mexican judges.

Mexican judges can act not only as protectors of individual human rights, as granted by international law, but also as guarantors of the international duties of an individual. At present, individuals are active subjects of international human rights law and passive subjects of international criminal law. According to the norms and principles of this specialized branch of international law, individuals have the obligation not to commit so-called international crimes, such as genocide, war crimes, crimes against humanity and crime of aggression. Even if the 20^th Century has witnessed the development of international criminal Courts and Tribunals (such as the International Criminal Court, the International Criminal Tribunal for ex-Yugoslavia or the International Criminal Tribunal for Rwanda), the jurisdiction of domestic courts is essential for the prosecution of these crimes. In fact, national courts are ordinary judges of international criminal law on two counts. All domestic judges are vested with the authority to perform so-called “universal jurisdiction”. Since the Eichmann case,²⁸ which was decided by Israeli tribunals after the Second World War, it has been admitted that domestic judges can hold individuals accountable for the commission of international crimes, even if the offender is not a citizen of their state and the crimes were committed abroad. All domestic judges in states that have ratified the Rome Statute are, by virtue of its provisions, “complementary judges to the International Criminal Court”.²⁹

Mexican judges have so far not admitted their role as international criminal law judges. There are no cases in which they have exercised universal jurisdiction, as such. However, in the Cavallo case, decided in 2003,³⁰ the Mexican Supreme Court accepted the extradition to Spain of an Argentine national for the commission of international crimes in Argentina.³¹ The Supreme Court emphasized that “the tribunals of a State can exercise, in the name of the international community, as a whole, jurisdiction over some crimes”, particularly over genocide, torture and terrorism. No cases have been decided, until now, on the ground of Mexican judges’ complementarity to the International Criminal Court, nor have they ruled on the recognition of individual criminal responsibility under international law.

2. Mexican Judges as Interpreters of International Law

As mentioned above, domestic judges will act as ordinary judges of international law whenever they apply and interpret international law norms and principles in cases brought before their jurisdiction. Articles 31 to 33 of the Vienna Convention on the Law of Treaties establish the principal methods of interpretation of international law, and most domestic judges have recourse to these methods.³²

Mexican judges have interpreted international law norms according to the same methods. The first case, rendered in 2002, dealt with the conformity of Mexican tax laws with the provisions of the Global Agreement on Trade and Tariffs (GATT).³³ By a unanimity of votes, the Mexican Supreme Court decided that the rules of interpretation of Articles 31 and 32 of the Vienna Convention are binding on the Court, but only if they don’t fall apart from the provisions of Article 14 of the Mexican Constitution. The Court found that Article 31 establishes three principal methods of interpretation: literal, systematic and teleological. International law scholars use the terms textual, systemic and teleological to refer to the methods of Article 31. These differences in language show an intent by the Mexican Supreme Court to “accommodate” the Vienna Convention’s methods to its own methods of interpretation, according to the provisions of domestic law.³⁴

In another case in 2002, the Mexican Supreme Court interpreted the Convention on the Prevention and Punishment of the Crime of Genocide, through the systematic (systemic) method, derived from Article 31 of the Vienna Convention.³⁵ In particular, the Supreme Court took into account the Convention’s travaux préparatoires and concluded that the political motives of the author of genocide are not one of its constitutive elements. In a more recent case, decided in 2004,³⁶ the Supreme Court considered the interpretation of North American Free Trade Agreement (NAFTA) and the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) should be carried out in accordance with Articles 31 to 33 of the Vienna Convention on the Law of Treaties. However, in that case, the court did not proceed with a detailed interpretation process of the above-mentioned treaties.

Mexican judges have not only been interpreters of international law, by the use of international law’s own methods of interpretation, as there are some recent cases where Mexican judges developed the so-called “consistent interpretation” technique. By way of this technique, domestic judges interpret national laws in conformity with the international law commitments of their respective States. Initiated in the US with the Charming Betsey Case in the US Supreme Court,³⁷ “consistent interpretation” is an obligation for some domestic judges, particularly in the European Union.³⁸ In other cases, the obligation of “consistent interpretation” is included in the Constitution of states.³⁹ Even with a lack of express obligation to do so, many domestic judges, in either monist or dualist countries, have interpreted domestic law in conformity with international rules and principles.⁴⁰ Consistent interpretation can render dualist systems, like Mexico’s, monist in some sense⁴¹ through the oeuvre of domestic judges. In fact, through consistent interpretation, domestic judges can use international law instruments not incorporated or otherwise received in their respective domestic legal order, so as to shape the meaning of national legal norms and principles.⁴²

Domestic judges use the “consistent interpretation” technique with more frequency when they have to apply domestic legal provisions to human rights protection. In fact, national judges, particularly those working in Supreme and Constitutional Courts, always try to show that their interpretations of human rights, granted by internal norms and principles, are in conformity with international human rights instruments.⁴³

Mexican judges are not separate from this global judicial movement toward consistent interpretation of domestic law with international human rights law. In some case law decisions, Mexican judges have interpreted national legal provisions in accordance with international human rights instruments. In 2008, a circuit tribunal considered that the illegal deprivation of liberty is contrary to Articles 1, 14, 16, 103 and 107 of the Mexican Constitution, and must be interpreted in accordance with international human rights instruments regarding the protection of the right to honor and reputation.⁴⁴ In an important 2011 case, the Supreme Court emphasized the importance of the interpretation of all domestic law in conformity with the objectives of human rights protections and related provisions of the Mexican Constitution and international treaties ratified by the Mexican state. The Supreme Court distinguished between two types of consistent interpretation: consistent interpretation in a broad and a limited sense. In a broad sense, it found that all domestic judges shall interpret the domestic legal order consistently with human rights, recognized in the Constitution and in international treaties... In a more limited sense, in the view of the Supreme Court of Mexico, “whenever there is more than one plausible interpretation, domestic judges shall prefer the one that is closer to the Constitution as well as to the international treaties to which the Mexican State is part”.⁴⁵ In the same case, the Supreme Court emphasized that a consistent interpretation shall always take into account the pro homine principle, which has become the guiding interpretative principle of the Court in the field of international human rights law.

The pro homine principle has been developed through the jurisprudence of international human rights courts, especially in the case law of the Inter-American Court on Human Rights. The pro homine principle is essentially an international human rights principle. By basing their own rules of interpretation in a hermeneutical principle of international (US) human rights law, Mexican judges have demonstrated that they feel bound by an international (human rights) judicial function.

A 2011 constitutional reform included the pro homine rule of interpretation of international and domestic human rights instruments in the first article of the Mexican Constitution.⁴⁶ Nevertheless, even before Constitutional reform, Mexican judges started to have systematic recourse to the pro homine principle. In a case, decided in 2004, a circuit tribunal affirmed

the pro homine principle is a hermeneutical principle, established in many international treaties and coincident with the fundamental nature of human rights. By virtue of this principle, human rights provisions shall always be interpreted in a broader sense when it comes to protecting human rights and in a more limited sense when it comes to restricting them.⁴⁷

One year later, another circuit court considered that recourse to the pro homine principle is not optative but obligatory, this because of its recognition in international treaties, which are part of domestic law and, thus are binding for Mexican judges.⁴⁸ In 2011, the Supreme Court confirmed the binding nature of the pro homine principle not only for judges, but for all State authorities. According to the Supreme Court: “all State authorities, in their respective spheres of competence, have the duty to apply norms, favoring at all times an interpretation that can afford a broader protection in favor of individuals”.⁴⁹

3. The Role of Mexican Judges in Assessing the Conformity of Domestic Legislation with International Law

In many domestic legal orders, the “conventionality control” (contrôle de conventionnalité, control de convencionalidad) refers to the obligation of domestic judges to control the compliance of domestic legislation with international law. The most advanced system of conventionality control was developed in the EU legal context. In the Simmenthal case,⁵⁰ the Court of Justice of the European Communities considered that domestic judges should leave all domestic provisions which are contrary to EU law “unapplied”.⁵¹ The judicial “non-application” of the rule doesn’t mean its formal abrogation, as it is an exclusive competence of the national legislators. However, it permits domestic judges to assure the efficacy of EU law commitments of their States and to protect the rights and duties EU legal norms grant to private persons. The Simmenthal doctrine has been one of the pillars of the conversion of domestic judges in EU member states to “ordinary judges of EU law”.⁵² Beginning in the early 1990s, national courts of EU member States accepted this role and started to control the compatibility of domestic legislation with EU law.

Another international court has recently developed the duty of domestic judges to assess the compatibility of national legislation with international human rights treaties. In the Almonacid Arellano vs. Chile case,⁵³ the Inter-American Court of Human Rights (IACHR) incorporated the Simmenthal doctrine in the Inter-American system in the following terms: “when States have ratified an international treaty, such as the American Convention on Human Rights, their domestic judges, as State officials, are also submitted to the treaty... Consequently, according to the IACHR, domestic judges have the duty to avoid an annulation of the Convention’s provisions effet utile in domestic legal orders by the application of domestic legislations that are contrary to its objectives and purposes. In other words, in the Court’s opinion, domestic judges shall perform some type of conventionality control between the domestic legal norms invoked in concrete cases before them and the American Convention on Human Rights.

The Inter-American Court affirmed that the assessment of the compatibility of national legislation with the American Convention amounts to some type of conventionality control (una especie de control de convencionalidad), when this, in fact, is the only type of conventionality control. This shows the misunderstandings human rights judges can have regarding core concepts of general international law. Even the Inter-American Court’s President Eduardo Ferrer considered in 2010 that the duty of national judges within the American Convention on Human Rights´ member States to control the conformity of domestic legislation with this treaty is a new type of “diffuse conventionality control” that gives them a “new mission” and converts them into “Inter-American judges”.⁵⁴ This is how a well-developed principle of international law at the European and global scale over the past decades has been recently discovered in the Latin American and the Inter-American contexts. Even if a legal basis for conventionality control has been present in Mexico’s Constitutional Article 133 since 1917,⁵⁵ Mexican judges have only recently started to perform conventionality control.

In 2005, a circuit court controlled the conformity of Article 128 of the Federal Code on Criminal Proceedings with Article 8.2 of the American Convention on Human Rights, declaring the non-compatibility of the domestic law provision with the international treaty.⁵⁶ In 2007, the Federal Electoral Tribunal reviewed the conformity of the Constitution of Baja California Sur with Article 25 of the International Pact on Civil and Political Rights and Article 23-2 of the American Convention on Human Rights, in relation with the possible restriction of the right to take part in public affairs and elections.⁵⁷ In a decision rendered in 2009, a circuit court found that the performance of conventionality control is a duty upon Mexican judges in the area of human rights protection.⁵⁸ The court considered that domestic judges must control conformity between national and “supranational norms,” in order to apply not only internal but also international legal instruments that afford protection of individual human rights. Also in 2009, another circuit tribunal asserted the compatibility of Article 190 of the Criminal Code of the state of Aguascalientes with Article 7 of the Universal Declaration of Human Rights and Article 26 of the International Pact on Civil and Political Rights.⁵⁹ In 2010, another circuit tribunal affirmed that “conventionality control shall be assumed by Mexican judges, in the resolution of cases brought before their jurisdiction, in order to verify that domestic legislation is not contrary to the objectives and aims of the American Convention on Human Rights”.⁶⁰ None of these cases dealt with the effects produced by conventionality control as regards the survival and/or future application of domestic legislation which is declared contrary to international human rights law.

The Mexican Supreme Court ruled on this question in an important case which was resolved in 2011.⁶¹ The Court incorporated almost to the letter the Simmenthal doctrine of the European Court of Justice, and ruled that, by virtue of Article 133 and Article 1 of the Mexican Constitution, Mexican judges have the duty to “prefer human rights, granted by the Constitution and international human rights treaties, even in the case of the existence of contrary provisions in any inferior rule”. The Court added that even if judges are not allowed to do a general declaration upon the validity of the contrary rules or remove them from the domestic legal order, they do have the duty to leave unapplied these rules and give preference to those contained in the Constitution and in the international treaties. The Supreme Court also considered that conventionality control concerns only human rights provisions of international law and represents a duty for all judges in the Mexican State than can be performed ex officio.

To date, there are few cases in which Mexican judges have accepted to control the conformity of domestic legislation with non human rights provisions of international law. My research found only one recent case where a Mexican tribunal reviewed the compatibility of domestic legislation with international law provisions related to the protection of intellectual property rights. In a decision, rendered in 2004, the Supreme Court controlled the conformity of domestic legislation on industrial property with the Mexican State’s commitments in NAFTA and TRIP agreements. The Court developed a double step proceeding in conventionality control. First, it asserted that the above-mentioned treaties have been legally incorporated in domestic law and, consequently, are part of the domestic sources of legality. After that, the Supreme Court showed that there is no incompatibility between domestic law provisions and these agreements. Instead, the Court emphasized that both provisions are not only harmonious but also complementary.⁶²

1. International Law in the Mexican Constitution

The place of international law in the Mexican Constitution is a very important limit for the scope of the international judicial function of Mexican judges. In fact, the Mexican Constitution includes few articles that deal with international law, and they are spread throughout the corpus of the fundamental norms. In particular, Articles 89, 104, 105, 117, 76, 15 and 133 deal with questions related to the sources of international law, their reception and incorporation in the Mexican legal order and their respective place in the internal hierarchy of norms. As will be demonstrated in what follows, the position of the federal judiciary towards these subjects is important.

With respect to the distribution of functions between the federation and federal entities (the states), the Political Constitution of the United Mexican States provides that the control of foreign policy belongs to the federation.⁶³ Regarding the distribution of functions between the three branches of the federation (the federal executive, the federal legislature and the federal judiciary), the Constitution designates an almost total power to the federal executive with regards to international relations. In Mexico’s presidentialist regime, the President of the Republic is the principal authority in matters of international law.⁶⁴ The Constitution expressly prohibits the federal executive from celebrating specific types of international treaties.⁶⁵ By virtue of these checks and balances, it is a combination of constitutional doctrine and legislative power that restrain the president’s foreign policy and approve the international treaties celebrated by the president.⁶⁶ Regarding the division between Federal and Local Judiciaries in the Mexican federation, “Federal Courts have jurisdiction over: II. Any civil or mercantile controversy arisen about the observance and enforcement of federal laws or international treaties signed by Mexico... VIII. All controversies regarding diplomats and consuls”.⁶⁷

The highest federal court (the Supreme Court of Justice of the Nation) is vested with the power to control the constitutionality of international treaties.⁶⁸ The Supreme Court has controlled the constitutionality of treaties in some concrete cases under its jurisprudence. In the 2003 Cavallo case, the defense tried to demonstrate the unconstitutionality of Articles V, VI and VII of the Convention on the Prevention and Punishment of Torture due to their incompatibility with the principle of self-determination of people and non-interference in domestic affairs, established in Article 89 of the Mexican Constitution. The Supreme Court rejected these arguments and considered that the treaty was not contrary to the Constitution.⁶⁹ In 2004, the Supreme Court clarified the consequences of a declaration of the unconstitutionality of a treaty;⁷⁰ in 2007 it considered all treaties to have a presumption of constitutionality.⁷¹

The submission of treaties to constitutionality control is questionable from the perspective of international law. In fact, the a posteriori constitutionality control of a treaty is contrary to the principle of pacta sunt servanda and amounts to a unilateral amendment of the legal instrument. As emphasized by the Supreme Court of Turkey in a recent case, “it is a universally accepted principle that treaties should not be submitted to a constitutionality control,” as this control is contrary to the reciprocity and equality that govern interstate relations in international law.⁷² Through the acceptance of unconstitutionality lawsuits against treaties, the Mexican Constitution and the Supreme Court are actually confirming the full supremacy of the Constitution over Mexico’s international law commitments.

Finally, Article 133 of the Constitution determines the hierarchy of international law within the Mexican legal order.⁷³ The text provides that the Constitution, treaties and federal laws “shall be the supreme law of the country”, without giving any more precision on the relationship between the three.⁷⁴ The Supreme Court resolved this question in more recent case law. Initially the Court proclaimed the supremacy of the Constitution over treaties and considered treaties to have the same hierarchy as federal laws.⁷⁵ Fortunately, the Court modified its position and in 1999 recognized that treaties have supra legislative rank, as they are superior in the hierarchy of norms to all internal laws.⁷⁶ The Supreme Court reaffirmed this reasoning in 2007. In a decision on February 13, 2007, the Court concluded that “international treaties are hierarchically inferior to the Constitution, but superior to federal, general and local laws”.⁷⁷

Additionally, in 2011, the Mexican legislature achieved an important constitutional reform in the area of human rights that modified the content of Article 1 of the Constitution, as well as the place of international human rights treaties in the Mexican legal order.⁷⁸ This provision placed international treaties that grant human rights to individuals on the same hierarchical level as the Constitution itself. In the area of human rights, it created a so-called “constitutionality bloc,” which includes constitutional and conventional provisions. In the words of the President of the Mexican Supreme Court, it marked the “Conventionalization of the Mexican Constitution”.⁷⁹ However, the reform was silent with regards to the resolution of a possible conflict between a human rights treaty and the Constitution. The Supreme Court had to interpret the new Article 1 and adjust the hierarchy between both legal instruments. In a case resolved in 2014,⁸⁰ the Supreme Court decided that if there is a “constitutional restriction” on the exercise of human rights granted by a treaty, the constitutional restriction shall prevail. The Court has since reaffirmed this solution.⁸¹

This Constitutional design of the place of international law in the Mexican legal order has important implications for the scope of the international judicial function performed by the Mexican federal judiciary. As stated above, the Constitution only includes references to treaties as a source of international law and completely ignores all other sources. Article 38 of the Statute of the International Court of Justice, which is binding for Mexico, lists at least two more formal sources of international law: custom and general principles of law. Additionally, there are modern sources such as unilateral acts of the State, resolutions of international organizations, international jurisprudence, soft law, gentlemen’s agreements, and so on.⁸² However, regarding its treatment of sources of international law, the Mexican Constitution is monothematic and seems to correspond to the level of development of international law sources doctrine common in the 19^th Century.⁸³ If Mexican judges use the Constitution as a legal guide for the application and interpretation of international law in their judicial practice, they could have recourse only to treaties as a source of binding international law norms. Custom and general principles of law, as well as other possible sources, would be absent from their case law. As we take a closer look to the case law of Mexican judges analyzed in the previous section, this indeed appears to be true.

As demonstrated in the first part of the article, Mexican judges have protected the private rights and duties of individuals under international law in some recent cases of jurisprudence. In all of these cases, Mexican judges based their protection in an international treaty. Again, the most prominent example is the judicial protection of human rights. All the cases analyzed had to deal with the human rights granted by treaties (especially the American Convention on Human Rights, the International Pact on Civil and Political Rights, the International Pact on Social and Cultural Rights, the UN Convention on the Rights of the Child, and the UN Convention on Prohibition of Torture). Recent jurisprudence by Mexican judges in this field have failed to mention other sources of international law.

The previous section of this article made clear that Mexican judges are interpreters of international law. All the cases where they had recourse to the methods of interpretation of the Vienna Convention on the Law of Treaties and all the cases where they utilized the “consistent interpretation” technique and developed the pro homine principle to deal with the interpretation of international treaties. From all the cases included in the first section of the article, none contains an interpretation of international customary law or general principles of law. Mexican judges have mentioned the existence of international customary law in only one case of their jurisprudence; in another case, they asserted the value of a soft law instrument within the Mexican legal order,⁸⁴ and in another they analyzed the existence of a jus cogens rule on the prohibition of torture.⁸⁵

The place of treaties as a unique source of international law in the Mexican Constitution can explain why the international judicial function of Mexican domestic judges, at present, is limited to the interpretation and application of treaty law only.

Another possible constraint on the international judicial function of Mexican judges is the special place of human rights treaties in the constitutional design for the reception and incorporation of international law in the internal legal order. As explained above, the 2011 constitutional reform in the human rights field elevated those treaties to a constitutional hierarchical level. This reform was particularly significant for Mexican judges with regards to their willingness to apply and interpret international human rights treaties in the performance of their international judicial function.

As shown in the first section of this article, the jurisprudence of Mexican tribunals has been devoted to the protection of individual human rights as set forth in international treaties. Additionally, the decisions examined above demonstrate that the interpretation of international law by Mexican judges has focused almost exclusively on human rights instruments. Mexican judges control over conventionality developed into a judicial review of the conformity of internal acts and legal norms with international human rights instruments. The only exception is the recent compatibility control of the Industrial Property Law with TRIP agreements and supranational bodies like the WTO and NAFTA.

As discussed, the special place of international human rights treaties in the Mexican Constitution seems to constrain the ability and willingness of Mexican judges to act as “ordinary judges of all international law”. So far, they have only accepted to be “judges of international human rights law”. The constitutional reform of 2011 significantly altered the place of international human rights in the Mexican Constitution, and Mexican judges became more aware of their international judicial function, in the specific area of human rights protection. Vast segments of general international law and its specialized branches (international economic law, international criminal law, international environmental law, international maritime law, etc) are still completely ignored by the Mexican Constitution and by Mexican federal judges.

Another constitutional constraint on the ability and willingness of Mexican judges to act as judges of international law is the hierarchy of international law in the domestic legal order. As explained above, the text of the Constitution and the jurisprudence of the Supreme Court both affirm the supremacy of Mexican Constitution over treaties, excepting human rights treaties. This situation can predispose Mexican judges to consider international treaties other than human rights treaties and international law in general as a subaltern and subsidiary legal order in its relation to domestic (constitutional) law. Another important consideration regarding the conception of the hierarchy of international law is the recognition, in the Mexican Constitution, and in the Supreme Court’s jurisprudence over the possibility to control the constitutionality of a treaty.⁸⁶

This vision of the supremacy of the Constitution over international law has permeated the lower Courts with regards to the limits of their international judicial function. The case law analysis of the previous section demonstrates that Mexican judges have applied and interpreted the norms of international law through their acceptance in domestic law, and only when they confirm existing provisions of domestic law. In other words, Mexican judges feel bound by domestic law considerations in the fulfilment of their international judicial function. In almost all cases reviewed over the course of this study, Mexican judges have tried to demonstrate that international law can apply because it is consistent with the Constitution. They usually cite constitutional provisions followed by provisions of international treaty law.⁸⁷ When they perform conventionality control, Mexican judges first have to assert that the treaties in question have fulfilled the constitutional conditions for incorporation into the domestic legal order.⁸⁸ When Mexican judges interpret international treaties, they use methods of interpretation of constitutional law only when they conform to constitutional methods of interpretation and are “accommodated” in the hermeneutical techniques of domestic law.⁸⁹ When these judges interpret domestic legislation in conformity with international law, they need to show its conformity with the Mexican Constitution. Thus, from the perspective of Mexican judges, international law appears to be a more persuasive argument, based primarily in domestic constitutional law. The supremacy of the Mexican Constitution over international law can explain why Mexican judges maintain “first loyalty” to domestic law and to the belief that they can apply international law only through the lens of the Mexican Constitution.

Some judges have expressed this clearly. When defining the value of soft law⁹⁰ a circuit court judge argued that the recognition of this value: doesn’t mean the original observance of the national legal order is disregarded. The court also insisted on “the subsidiary nature of supranational norms, by whose virtue, the international protection of human rights is only applicable after the exhaustion, and with the failure of internal safeguards. During the discussion in the Supreme Court surrounding its last pronouncement on the hierarchy of international human rights treaties, Margarita Luna Ramos, one of few female judges in Mexico said that “To recognize the supremacy of international treaties over the Mexican Constitution is to sell the motherland”.⁹¹

The dualism of the Mexican Constitution has determined the legal mindsets and beliefs of Mexican judges. Mexican judges see themselves as domestic judges and guardians of the Mexican Constitution and the internal legality of Mexican law, and not as “ordinary judges of all international law”. The sovereign and protective spirit of the Mexican Constitution is a product of many centuries of Mexican social and political history, characterized by foreign invasions,⁹² United States imperialism and foreign interferences of all types in internal affairs. One can easily understand why Mexican judges may harbour an innate instinct of protection and preservation of the autonomy of the Mexican legal order in the face of foreign elements, including international law. The legal nationalism of Latin American countries may be the most important constraint on the fulfilment of an international judicial function by Mexican judges. The loss of sovereignty that this would entail is mixed with the fear and rejection of the legal otherness in Mexico’s young and still fragile democracy.

2. Mexican Judges and Deference to the Executive Branch in Foreign Affairs

The specific relationship between domestic judges and the executive branch can be decisive for the potential of these judges to become international law judges.⁹³ From a domestic legal perspective, state governments apply laws within the limits established in a national constitution. In international law, governments are political powers that exercise effective control over their territory and citizens. Although international law distinguishes states from their governments, the foreign policy of states is adopted and executed by government officials. It is they who decide to enter in diplomatic and consular relations with other governments; who negotiate and sign international treaties and whose wrongdoing can compromise a state’s international responsibilities. Consequently, the norms of international law have to do primarily with the legal regulation of governmental acts at the international and internal level.

In all countries, domestic tribunals are, of course, independent from the executive branch. However, when they control governmental conformity with international law, domestic judges can restrain governmental margin of appreciation in the implementation of foreign policy objectives. Judges can even adopt judicial decisions that contradict those objectives. Thus, the general dynamics of interaction between domestic judges and the executive influences their ability and willingness to assume an international judicial function.

As Benvenisti shows,⁹⁴ when the application of international norms by national courts is sought in an attempt to constrain the activities of the executive branch, domestic judges might be more timid and reluctant regarding their potential in the international arena. In the author’s opinion, a judiciary that is formally independent from the executive branch of the government might seem a perfect forum for the application and enforcement of international law in the domestic legal order. However, the jurisprudence of domestic judges seems to be consistent in protecting short-term governmental interests. Judges are careful not to impinge with their decisions on the international policies and interests of the government.⁹⁵

The tendency for domestic judges to rule on international law issues in favor of the interests of their executive branch has been a driving force behind the creation of various international dispute settlement mechanisms. One of the main reasons for the success of international commercial and investment arbitration is the fact that arbiters are not state agents and are supposed to be more independent than national judges are when they apply or interpret international law.⁹⁶ In the same sense, the International Center for Settlement of Investment Disputes (ICSID) Convention expressly provides for a non-application of the rule of exhaustion of local remedies in international investment arbitration cases. The NAFTA arbitration system and the creation of international courts and tribunals casts doubt on the ability of domestic judges to preserve the efficacy of the norms and objectives of international law when it goes against the will of their own government.

In the Mexican context, the deference of domestic judges to the executive branch in foreign affairs matters is one of the mightier limits to their ability to perform an international judicial function, as well as to their perception of themselves as ordinary judges of international law. This political constraint essentially relates to the capacity of Mexican judges to review foreign policy actions and decisions taken by the executive power under international law. In this sense, the international judicial function of Mexican judges turns out to be, fundamentally, a rule of law function, which seeks the subordination of the executive branch to that of international law.

Mexico is a young democracy. The evolution of the Mexican political system, as a whole, has represented a true challenge to the ability of the judiciary to guarantee the respect for the rule of law. The division of power in the Mexican Constitution is characteristic of a presidential regime. However, the dominance of the hegemonic Institutional Revolutionary Party (PRI) on the political landscape during the second half of the 20^th Century distorted the checks and balances of the regime in favor of the executive branch. For many years, Mexico’s President has been an all-powerful legal and political figure, this executive “preponderance”⁹⁷ over the other two branches of the state (legislative and judicial) has been called a perfect dictatorship. The omnipresence of the executive in relation to the judiciary⁹⁸ affected the independence of the judicial branch, which was formally recognized in the Constitution but did not exist in reality. Consequently, Mexican judges were not able to develop strong judicial oversight of governmental activities. Their judicial function throughout this period fell away from guaranteeing respect for the rule of law within the Mexican legal order.

Before 1990, the relation Mexican judges had with international law was utterly distant.⁹⁹ The number of international law related questions raised in internal proceedings before Mexican Judges was extremely limited. Additionally, case law decisions from that time showed Mexican judges had serious doubts regarding basic notions of international law. In 1985, the Plenary of the Mexican Supreme Court was still questioning whether international treaties are acts that need legislative motivation¹⁰⁰ and whether these treaties possess a legislative nature.¹⁰¹ In 1990, circuit tribunals had to determine if the existence of a treaty needs to be proven by the party that invoked it, and how treaties were to become part of the domestic legislation.¹⁰²

The judicial reform adopted in 1994 was important because it tried to guarantee the independence of the Mexican federal judiciary. This coincided with a new willingness on the part of Mexican tribunals to deal with international law.¹⁰³ The slow democratization of the Mexican political system was complementary with a modification of the priorities of the foreign policy objectives on the part of the executive branch. In fact, the executive began to adopt a more liberal foreign policy based in a necessary change in the location of international law within the domestic legal order. In 1992, President Carlos Salinas de Gortari decided to open the Mexican economy to globalization. The signing of NAFTA represented an important inflexion point in the move towards a better reception mechanism for international law within the domestic legal order.¹⁰⁴ In 1998, Mexico accepted the compulsory jurisdiction of the IACHR.¹⁰⁵ Those two events sparked a slow internationalization of the Mexican legal order.

The Mexican federal judiciary began to perform an international judicial function around the same time. Most of the cases analyzed in this article date from the end of the 1990s and the beginning of the 2000s. The late and slow democratization of the Mexican legal order culminated with the victory of Vicente Fox Quesada of the National Action Party (PAN) in presidential elections in the year 2000, which allowed a more active role for Mexican judges with regards to the subordination of the executive under the law. The internationalization of the Mexican legal system, promoted by the executive branch, brought a change in attitudes among Mexican judges regarding the possibility of ensuring the legality of governmental acts under international law.

However, even after 2000, the jurisprudence of Mexican judges in matters related to international law revived “their previous self-perception as subordinated to the Executive Branch to which deference was owed in questions of international law.”¹⁰⁶

In this sense, my analysis in the previous section demonstrates how decisions adopted by Mexican judges have always narrowly interpreted the articles of the Mexican Constitution that deal with the incorporation and hierarchy of international law in the domestic legal order. In doing so, they have reduced their own possibility of controlling the legality of governmental acts under international law.

The Supreme Court’s refusal to recognize the existence of and to consider sources of international law outside of treaties shows the persisting deference of the Supreme Court to the executive power on foreign affairs. The court only mentions treaties in its case law, because treaties are the best expression of state’s consent to the creation of rights and duties on its governmental power. Mexican judges have thus adopted a positivist vision regarding the sources of international law, which consider the only valid sources of international law as those which express governmental consent as bound by legal rules.¹⁰⁷ This vision expresses the rejection of the possibility of creating legal limits to governmental action in international law against the expression of free will on behalf of the executive branch.¹⁰⁸ This consent is particularly easy to prove in the case of treaties. Treaties are direct expression of the will of states to create reciprocal and binding rights and duties under international law. It is generally admitted that international treaties are analogous with contracts in domestic law.¹⁰⁹ The state’s consent to the two other sources of international law, as stated in Article 38 of the Statute of the International Court of Justice (custom and general principles of law) is more difficult to establish.¹¹⁰ Consequently, Mexican judges have a tendency to apply treaties only in the performance of their international judicial functions, as only this source of international law is government consent friendly regarding the imposition of legal limits to the executive power in foreign affairs related matters.

The refusal of Mexican judges to establish the supremacy of international treaties (including human rights treaties) over the Mexican Constitution demonstrates their unwillingness to reign in governmental power and reduce the government’s margin of influence beyond the limits of the domestic constitutional order. Mexican judges will not interpret constitutional provisions regarding the hierarchy of international law in the internal system in a way that would increase their power to influence the executive’s respect for international law.

As discussed earlier, the only field where Mexican judges have taken their international judicial function seriously, without deference to the executive branch, is in the protection of human rights. This shows that they have a particular understanding of their role as guardians of the international rule of law. It seems that Mexican judges are willing to control governmental actions related to international law only when those actions constitute human rights violations. In all other cases, they fulfill their judicial review function regarding the legality of the actions of the executive in accordance with domestic law.