Back in 2003, Mexico enacted linkage regulations to avoid the granting of marketing authorizations in violation of patent rights.  The system created by these regulations is far less elaborate than the one set forth by the Hatch-Waxman act in the U.S., as there is no extension/term restoration, and there is no possibility for Paragraph IV-type applications.
This system was intended to be simple:  two provisions were added to the health and IP law regulations establishing that the Mexican Patent Office (IMPI) is bound to publish a specific gazette every six months, listing those patents in force that cover allopathic drugs.  The regulatory authority (COFEPRIS) has to observe the patents listed in this gazette, request information from IMPI if necessary, and deny applications for marketing authorizations which would invade patent rights.
Nevertheless, controversy arose from the moment the provisions were enacted.  IMPI immediately stated that the linkage benefit would only be applicable to patents covering active ingredients per se, and therefore formulation patents were not to be listed nor observed by COFEPRIS.  Thus, the first gazette was published including only active ingredient patents.

R&D Pharma companies decided to challenge this criteria through individual constitutional actions before Mexican District Courts, arguing that a correct interpretation of linkage provisions should cause for all pharmaceutical product patents to be published.  Most courts agreed on this, resulting in over 40 decisions in favor of patent holders over a period of six years.  The vast majority of these cases were handled by the Mexican IP Firm Olivares & Cia.
As two Circuit Courts issued opposing decisions, indicating that the linkage system was indeed limited only to active ingredient patents, the case was brought to the attention of the Mexican Supreme Court, which recently made its decision public.
In a closely contested 3-2 decision, the Supreme Court determined that product patents, including those covering pharmaceutical formulations are to be included in the Gazette.  The Court also made reference to the co-related obligation by COFEPRIS to observe these patents.
Even though this decision is only mandatory for Courts, and not for administrative authorities, we expect that both IMPI and COFEPRIS will observe it, which is a step in the right direction for a strong IP system in Mexico.
Source: Patent Docs, 2010.