Constitutional Review in Mexico: Abstract and Concrete Control

Introduction

Mexican constitutional review operates through a dual system of abstract and concrete control, blending elements of the Kelsenian centralized model and the American diffuse model. The action of unconstitutionality (acción de inconstitucionalidad) provides for abstract review before the SCJN, while the amparo remedy enables concrete review by any federal judge. The constitutional controversy (controversia constitucional) resolves disputes between levels and branches of government.

Abstract Review: Acción de Inconstitucionalidad

The action of unconstitutionality allows specific authorized bodies (including the CNDH, minority legislative factions, and political parties) to challenge the constitutionality of laws, treaties, and regulations before the SCJN within 30 days of their enactment. The review is abstract — it examines the law’s consistency with the Constitution without requiring a concrete case or controversy. A declaration of unconstitutionality requires an eight-vote majority and produces general effects (efectos erga omnes).

Concrete Review: Amparo

The amparo remedy provides concrete constitutional review by allowing individuals to challenge laws, acts, or omissions that violate their constitutional rights. Amparo may be filed against laws (amparo contra leyes) or acts of authority (amparo contra actos). The review is concrete — it arises from a specific case where the applicant claims a particularized injury. The effects of an amparo judgment are generally limited to the applicant (the “Otero formula”), though the SCJN may extend general effects through jurisprudencia.

Constitutional Controversies

Constitutional controversies (controversias constitucionales) are proceedings before the SCJN that resolve disputes between: the federal government and a state; two or more states; a state and Mexico City; or branches of the federal government. These controversies address conflicts over jurisdiction, powers, and authority, ensuring compliance with the constitutional distribution of powers.

Conventionality Control

Since the 2011 human rights reform and the SCJN’s ruling in Caso Radilla Pacheco, all Mexican judges are required to exercise conventionality control (control de convencionalidad) — reviewing domestic laws for consistency with international human rights treaties. This diffuse control obligates all courts to prioritize international human rights norms and, where necessary, to disapply domestic laws that violate treaty obligations.

Conclusion

Mexico’s dual system of constitutional review combines centralized abstract review through the SCJN with diffuse concrete review through the amparo remedy. The addition of conventionality control has expanded the scope of constitutional review, requiring all judges to ensure consistency between domestic law and international human rights standards.