Criminal Procedure in Mexico
Introduction
Criminal procedure in Mexico is governed by the National Code of Criminal Procedure (Código Nacional de Procedimientos Penales, CNPP), enacted in 2014 and implemented nationwide by 2016. The CNPP implements the 2008 constitutional reform that transformed Mexico’s criminal justice system from an inquisitorial written model to an accusatorial adversarial model. The reform fundamentally restructured criminal investigations, pretrial procedures, trial, and appeals.
Constitutional Framework
The 2008 constitutional reform amended Articles 16, 17, 18, 19, 20, 21, 22, 73, 115, and 123 to establish the accusatorial system. Article 20 guarantees the principles of: publicity, contradiction, concentration, continuity, orality, and immediacy. The reform established the presumption of innocence, the right to silence, the right to counsel, and the right to confront witnesses.
Investigation Phase
Criminal investigation is conducted by the Public Prosecutor’s Office (Ministerio Público), assisted by investigative police. The investigation is recorded in the carpeta de investigación (investigation file). The Public Prosecutor may seek judicial orders for searches, wiretaps, and pretrial detention. The investigation must be completed within set time limits (typically six months, extendable).
Pretrial Procedure
The pretrial phase includes: the initial hearing (audiencia inicial), where the accused is informed of the charges, a judge reviews the legality of the detention, and precautionary measures are decided; the formal charging hearing (audiencia de vinculación a proceso), where the judge decides whether sufficient evidence exists to bind the accused to trial; and the intermediate hearing (audiencia intermedia), where the parties disclose evidence, agree on facts, and the trial judge is assigned.
Oral Trial
The oral trial (juicio oral) is the central phase of the accusatorial system. The trial is conducted before a judge (or panel), with the prosecution and defense presenting evidence orally. The trial includes: opening statements; presentation of prosecution evidence (witness examination, expert testimony, documentary evidence); presentation of defense evidence; closing arguments; and the judgment. The standard of proof is beyond a reasonable doubt.
Appeals and Post-Trial
The judgment may be appealed through the recurso de apelación before a superior court. The appeal may challenge factual findings or legal errors. Exceptional remedies include the recurso de casación and the amparo remedy against final judgments. The principle of double jeopardy (non bis in idem) prevents retrial after acquittal.
Conclusion
The CNPP has transformed Mexican criminal procedure, establishing an accusatorial system that respects the presumption of innocence, ensures procedural fairness, and provides effective mechanisms for truth-seeking and accountability. The oral trial format has increased transparency and public confidence in criminal justice.