Divisional patent application practice in Mexico has undergone significant change since the entry into force of the Federal Law of Protection of Industrial Property (FLPIP) in 2020. While most of the FLPIP rules were initially understood as confirming the historically flexible practice for divisional applications, subsequent objections revealed an internal directive aimed to limit divisional-related procedural opportunities.
The FLPIP Regulations, published on April 28, 2026, introduce additional limitations that not only confirm the Mexican Institute of Industrial Property (MIIP)’s interpretation of the law, but also add new restrictions to divisional filings, effectively turning Mexico’s divisional practice one of the most restrictive in the region.
Definition of “initial” application
The FLPIP requires voluntary divisional applications to be filed while the initial application is pending but does not define what constitutes an “initial” application. The Regulations of the former law used the same wording, which was interpreted by the MIIP broadly, as including the first-filed application in Mexico as well as any later divisional application.
However, after the FLPIP entered into force, the MIIP adopted a narrower interpretation, considering that a divisional application could not qualify as an “initial” application for purposes of further division. This interpretation has affected second- and later-generation divisional applications, including those filed when the prior, more flexible criterion applied. Despite several appeal decisions, the Courts have not established case law clarifying the meaning of “initial” application.
Against this backdrop, the FLPIP Regulations codify MIIP’s current criterion: an initial application is “that which is filed for the first time, or, where applicable, that which claims priority for the first time, from whose filing date the corresponding divisional application pretends to benefit”. This definition operates together the FLPIP’s general prohibition against dividing a divisional, except at the request or discretion of the MIIP.
If voluntarily dividing a divisional application was already an uphill process requiring appeals, the new definition introduces a time constraint of great relevance. Since second- and later- divisional applications in Mexico are often filed years after prosecution of the first application has concluded, filing of such divisional applications will need to be made considerably earlier.
Dividing a divisional application after a lack-of-unity finding
The FLPIP allows the division of a divisional at the MIIP’s request. In particular, where a lack-of-unity objection is raised, the MIIP must request a division, thereby entitling the applicant to file a corresponding divisional application.
Under the FLPIP, the time for filing a “required” divisional application is within the term for responding to the Office Action containing the lack-of-unity objection. Here, the law makes no reference to the status of an “initial” application as a condition of admissibility of the divisional. Also, there are no restrictions to pursue the non-unitary inventions in a later voluntary divisional application.
The FLPIP Regulations have introduced two major restrictions in this context.
First, the initial (i.e., first-filed) application, must be pending. Therefore, like voluntary divisional applications, non-unitary divisional applications become tied to the initial application’s procedural status.
While this requirement is generally met for first-generation divisionals, it poses practical difficulties for later-generation divisionals. Because no official mechanisms to delay or suspend an application’s examination exist, applicants have little control over the progression of the procedure of an application. As such, any examination delays in the divisional will be detrimental to the ability to further divide the application. In practice, the initial application’s pendency may, and probably will, end before a lack-of-unity objection can be raised in the divisional.
Coupled with an extraofficial, but possibly still standing, directive that pauses examination of a divisional as long as the earlier application remains pending, the new FLPIP Regulations de facto bans second- and later-generation divisional filings.
Second, the FLPIP Regulations establish the effects of not filing divisional applications upon MIIP’s request (after a lack-of-unity finding), as being that “the subject matter of the division will be deemed not to have been claimed”.
Despite the convoluted wording, this rule may confirm MIIP’s practice of i) refusing to examine an invention other than that which appeared first in the claim set when examination begun, despite applicants’ attempts to prompt examination of a different invention, and ii) forcing the filing of all divisional applications as necessary after a lack-of-unity objection. Maintaining the remaining inventions in the application despite the objection would then equate to removing them from prosecution.
Applicant’s basic procedural right to traverse the objection is severely harmed with such limitations, especially since MIIP’s position is not to reissue lack-of-unity objections. Filing arguments against the objection risks that the MIIP is not persuaded, because the objection’s traversal dos does not pause or reset the term for filing the divisional applications. Thus, the MIIP continues examination of the first claimed invention only while ignoring the remaining matter.
Subject-matter restrictions for voluntary divisional applications
The FLPIP already includes subject-matter restrictions for divisional applications, such as the requirement that divisionals claim a different invention as compared to the family applications, as well as the prohibition of double patenting.
The FLPIP Regulations introduce an additional limitation: a voluntary divisional application may not claim subject-matter that was previously identified in a lack-of-unity objection but not pursued in a required divisional application.
This rule blocks the previously acceptable practice of pursuing through a voluntary divisional application such subject matter at a later stage and well after the statutory term for replying to the lack-of-unity objection lapsed.
In view the above, applicants will have a narrower window to decide on the filing of divisional applications.
Entry into force
The FLPIP Regulations enter into force on July 23, 2026, and will apply to patent applications filed since that date.
Although no reference is made to divisional applications stemming from applications filed under the previous rules, per MIIP’s practice, the FLPIP Regulations will likely apply to said divisional applications as well.
Pending patent applications filed prior to July 23, 2026, will continue prosecution under the former Regulations.
Conclusion
The FLPIP Regulations reinforce a restrictive approach to divisional applications in Mexico. Applicants may need to adjust prosecution strategies and anticipate decision-making, particularly in complex cases requiring multiple filings to obtain valuable coverage.
The exact reasons behind such policy against divisional filings are unknown. No public statement or explanatory guidelines have ever pointed out the need to reduce or limit divisional filings. Similarly, no scholar, NGO or stakeholder study of the divisional practice in Mexico has shown abusive or unfair practices that deserve control. Even if that were the case, the implemented measures raise questions on their proportionality.
Despite the restrictions, it remains true that the text of the FLPIP allows for alternative, patent-friendlier interpretations, and that the law’s higher hierarchical position can trump implementing regulations having weak legal basis. Hence, resorting to appeal remains a relevant tool in appropriate cases.