Oaxaca Usos y Costumbres (Sistemas Normativos Indígenas) — 417-418 de 570 Municipios

Oaxaca is Mexico's most Indigenous-diverse state: 570 municipios (municipalities), 16 recognized Indigenous ethnic groups, and the most complex Indigenous legal framework in the country. 417-418 of those 570 municipios govern themselves under Sistemas Normativos Indígenas (SNI — colloquially "usos y costumbres") rather than the standard Mexican political-party electoral system. The captures this sui generis political governance overlay as unique in the T1+ cohort.

Under the SNI framework, participating communities select their municipal authorities (presidents, counselors, committees) through traditional community assemblies, deliberation, and consensus processes rather than secret ballot and political party competition. The legal basis is the Constitución Política del Estado Libre y Soberano de Oaxaca + IEEPCO (Instituto Estatal Electoral y de Participación Ciudadana de Oaxaca) regulations, grounded in CPEUM Art 2 Apartado A fracción III and VII.

The TEPJF (Tribunal Electoral del Poder Judicial de la Federación) has developed an extensive body of jurisprudencia recognizing SNI legitimacy while also adjudicating cases where SNI processes allegedly violated individual voting rights under CPEUM Art 35. The balance between Indigenous collective political autonomy and individual political rights has generated some of the most nuanced electoral jurisprudence in Mexican law.

• Constitutional anchor: CPEUM Art 2 Apartado A fracción III (Indigenous communities' right to apply their own normative systems in regulating and resolving their internal conflicts) + fracción VII (Indigenous communities' right to elect in accordance with their norms, procedures, and traditions their authorities or representatives)
• State constitution: Constitución Política del Estado Libre y Soberano de Oaxaca (Art 25 — SNI recognition)
• Electoral authority: IEEPCO (Instituto Estatal Electoral y de Participación Ciudadana de Oaxaca) — catalogue and oversight of SNI communities; apex review by TEPJF
• Federal review: TEPJF Sala Superior — jurisdiction over SNI electoral disputes brought on constitutional grounds (Art 99 CPEUM)
• Operative period: CPEUM Art 2 reform 2001-08-14 → present; Oaxaca SNI recognition predates federal reform (1990s state-level reforms)
• Scope limitation: SNI applies to municipal elections only; federal and state-level elections in Oaxaca use the standard partido político / INE framework