Mexico has a Free Trade agreement with the USA. Such agreements are usually thought to require the patentability of software ideas, but software is reportedly explicitly excluded in Mexico's agreement (NAFTA).
Article 19 lists what is excluded and item 4 on the list is "programs for computers":
- ARTICULO 19.- No se considerarán invenciones para los efectos de esta Ley:
- IV.- Los programas de computación;