Every nation, whether formal or material, possesses a constitution. Firstly, it outlines the state, its components, its functioning, as well as the political organization of the territory and population. This "organizational" part is obviously tailored to a specific state, and there is no way to consider that these norms could be applied in another state. Secondly, the constitution contains a set of citizen protections against the state: fundamental rights. It should be noted that in the case of federal states, each federative entity has its own local constitution. However, these constitutions are, on one hand, subordinate to the federal constitution, and on the other hand, presume a territorial application, as indicated, for example, in the constitution of Nuevo León, a Mexican federated state:
"In the State of Nuevo León, all persons shall enjoy the human rights recognized in this Constitution."
Therefore, there is no scenario that would allow for application beyond Mexican territory. Concerning the potential "extraterritorial" application of the Nuevo León constitution within the territory of another federative entity, this is a matter of local law and is not the subject of our study.
Presently, the world is marked by both globalization and uniqueness. The first world consists of presupposed universal human rights. The second world is that of constitutions and their national particularities. Due process is universal; the constitutional prohibition of the Law of Primogeniture is Texan. With the proliferation of human rights, one must wonder what remains of fundamental guarantees. In a global view, they vanish in the realm of human rights. In a world of sovereign states, constitutional rights survive and, in extreme cases, can contradict human rights.
It may seem incongruous to ask who is entitled to constitutional protection. In Mexico, the answer is simple: all those within Mexican territory, regardless of their migratory status. However, other perspectives exist. For example, a certain school of thought in the US denies protection to non-resident foreigners because they are not part of the social contract. Indeed, the American constitution is considered a true social contract through which rights are granted to citizens, but also come with obligations. Non-resident foreigners, however, claim rights without bearing corresponding obligations. There are no rights without corresponding obligations, at least in the view of this doctrine.
Additionally, over the past few decades, there has been a proliferation of international judicial and arbitral decisions ordering a state to fulfill an international obligation. First, we find judgments on human rights, whether from the European Court of Human Rights (ECtHR) or the Inter-American Court of Human Rights (IACtHR), for instance. Second, there are judgments of the International Court of Justice (ICJ) and awards from various international investment arbitration tribunals that have confronted national constitutions. Indeed, more and more, states refuse to comply with what has been ordered on the grounds that the international decision is incompatible with the national constitution. In summary, we want to study how a constitution is applied in the presence of an element of foreignness and what the solution should be when an international decision violates the fundamental text, leading us to address the issue of the hierarchy of norms: is international law superior to the constitution, or is it the reverse?
In practice, two situations exist. First, a priori, the amparo or habeas corpus judge must decide whether the constitution applies, even if the act complained of by the defendant occurred outside national territory, particularly concerning the suspension of the act in question. Second, there is at least hypothetically, the case of applying a foreign constitutional norm. In all cases, it appears that we can speak of issues related to extraterritorial application.
The second part of our intellectual curiosity deals with an issue of intraterritoriality. A decision outside the national legal order, constituting an element of foreignness, seeks to be applied within the national territory. We will not consider the judicial decisions of foreign state courts, which fall under the domain of Private International Law, but rather international tribunals such as the ICJ or international investment arbitration tribunals. Two examples can illustrate this. The detention of non-U.S. "terrorists" in Guantanamo Bay, which is not part of U.S. territory, raised the question of whether these prisoners had rights under the American constitution. The second issue can be exemplified by the Avena case, where international law, through the ICJ ruling, appears to compel the United States to depart from its constitutional doctrine of the separation of powers, as a priori the U.S. executive would have had to compel the judicial branch to reopen the cases of Mexican death row inmates whose consular rights were violated. Obviously, this is a simplification of the issue for pedagogical purposes.
Moreover, due to the incorporation of human rights treaties into the constitution, it is worth asking if what has been discussed previously still makes sense, or if there is a need to differentiate between constitutional guarantees and human rights. Such a distinction seems to make sense in Mexican law, following the reflection of Minister Alfredo Gutiérrez Ortiz Mena. He states:
"It should be noted that, in my opinion, in most cases, a human right is a fundamental right, but not all fundamental rights are human rights. The ruling appears to define human rights as the genus and fundamental rights as the species, which is incorrect. Human rights and fundamental rights should not be related merely by conceptual breadth, but by normative delimitation. Depending on the content and normative status of each subjective right, it can be categorized in one way or another, or both. In this sense, I believe that the modification to Article 1 of the constitution did not intend to completely depart from the Supreme Court's jurisprudential theory. As can be seen from the amendment procedure itself, the purpose of the constitutional amendment of June 10, 2011, explicitly aimed to incorporate the concept of human rights from international law into the Constitution with all its normative weight, to recognize and protect the human rights provided in international treaties. In other words, the legal concepts set out in Article 1 of the Federal Constitution do not exhaust the content of rights predicable of the Constitutional Text. Namely, in our Fundamental Norm, there are subjective rights that must be considered as fundamental but are not strictly human rights."
The defining characteristic of human rights is that they are based on the intrinsic dignity of the human being, so they are recognized but not granted by the state. They are characterized by their universality, interdependence, indivisibility, and progressiveness. In contrast, fundamental rights are constitutionalized rights with a wide variety of content and limitations that do not necessarily need to comply with the characteristics of universality or progressiveness. For example, a constitution might guarantee that any authority must respond to petitions within 72 hours. Such a guarantee is obviously not a human right. In other words, international human rights are a minimum, while the constituent has the freedom to provide more protections than those protected by human rights. The differentiation between human rights and constitutional rights leads us to focus solely on constitutional rights to construct the notion of International Constitutional Law ("ICL").
The idea of exploring a new subject called ICL is due to the Russian professor Boris Mirkine-Guetzévitch, who, at the Institut des Hautes Études Internationales de Paris, had already published a work in 1933 called "International Constitutional Law." However, its content was more focused on the hierarchy between domestic law and international law than on a new subject. For our part, if the hierarchy of norms is an important part, it is not the only one, as we also address extraterritorial application of the constitution, constitutional control of international tribunal decisions, and more. Subjects of study that prevent us from confusing ICL with International Constitutional Law, which aims to study the "constitutional" organization of the international order, among other things, in relation to the United Nations Charter. Without being confused with other branches of law, it finally raises the question of whether it constitutes a new branch of law. Indeed, public international law is now more than ever a subject with various compartments. Its divisions, which tend to multiply, are complex. It is common to consider international economic law, international space law, international maritime law, and so on. However, the concept of a legal branch varies depending on the philosophical perspective adopted. The most suitable one appears to be the tripartite approach based on sociological, normological, and dikelogical axiological peculiarities, as elaborated by Werner Goldschmidt (1987). This approach refers to a set of cases with their own solutions (sociological dimension), cases and their solutions understood through norms and their unique methods (normological dimension), and all of them evaluated according to special justice requirements (dikelogical dimension). It regulates situations with an element of foreignness, which are not addressed by constitutional law (sociological dimension), and resolves conflicts between constitutional and international norms that cannot be resolved by either constitutional law or international law (normological dimension). These conflicts are not few and have very significant consequences, which necessitate a new conceptual framework to arrive at just solutions (dikelogical dimension).
In this sense, International Constitutional Law (ICL) is an essential subject that studies the phenomenon of foreignness, which is distinct, different from the usual. In other words, it explores how the constitution operates in relation to the usual and the "foreign." More specifically, it conceptualizes the rules for applying fundamental guarantees in the presence of an element of foreignness, whether it's the foreign nationality of a resident within the national territory or the execution of a judgment from an international tribunal that appears to violate these guarantees or constitutional principles. It's in this context that our subject distinguishes itself from Constitutional Law, which typically does not delve into these matters. Consequently, ICL aims to study the application of the Constitution in the presence of foreign elements, both within and beyond its national territory. Our approach will primarily be based on the Mexican constitution, complemented by comparative law, to avoid limiting the subject to a mere national perspective and identify criteria and rules that can potentially apply under any constitution (Part I). Furthermore, we seek to resolve conflicts arising from the intrusion of international norms or decisions into a country's constitutional organization (Part II). Given that extraterritoriality is a recurring theme in this study as a factor of foreignness, it's essential to define what is meant by territory and nationality, which also represent links of jurisdiction under jus gentium, owing to their sovereignty (Preliminary Title).....
La idea de explorar una nueva materia denominada DCI se debe al profesor ruso Boris Mirkine-Guetzévitch quien en el Institut des Hautes Etudes Internacionalde París, ya había publicado en 1933 una obra denominada Derecho constitucional internacional, sin embargo, el contenido era más centrado en la jerarquía entre el Derecho interno y el Derecho internacional, que en una nueva materia. Por nuestra parte, si la jerarquía de las normas es una parte importante, no es la única en la medida de que tratamos también de la aplicación extraterritorial de la constitución, el control constitucional de las decisiones de los tribunales internacionales, etc.
 El IHEI forma parte de la Universidad de París II Panthéon-Assas.