Interpretation of patent claims: recent court rulings

In the past year, a couple of court rulings from the Circuit Collegiate Courts were considered relevant for the interpretation of claims in Mexico in litigation. Both of these court rulings are not binding (i.e., "tesis aisladas" – non-binding court precedents), so a judge or collegiate court in a subsequent and similar case is not legally obliged to decide the current case in the same way as the previous one. However, these court rulings are an important reference for providing more clarity about some issues that did not have an official interpretation so far, and they may be discretionally used in the future, even when such application is not mandatory.

Both rulings were related to the same case and were published in the Mexican Federal Judicial Weekly on November 16 2016. This bulletin contains the published case law of Mexico. One ruling has to do with the concept of unity of invention and the other one is related to a concept similar to the long discussed doctrine of equivalents.

The first ruling establishes that the concept of unity of invention does not constitute a method in a litigation procedure to determine whether there is an infringement or not of a granted patent.

Article 43 of the Mexican Industrial Property Law (MIPL) defines that a patent application must refer to a single invention or to a group of inventions related to each other in a way they conform a unity of invention. Besides, Article 42 of the Regulation of MIPL sets up that the substantive examination of a patent application includes determining the compliance of the referred Article 43 of the MIPL. Thus, the ruling recognises that this concept is important for determining suitability of protection of the subject matter of a patent application.

Nevertheless, this ruling also states that Article 43 of the MIPL does not provide any basis for determining if an allegedly infringing product or process falls within the scope of a patent. The ruling clarifies that unity of invention is a requisite only during prosecution in order to assure that a granted patent will not be complex, that is, that it will not refer to several inventions.

It is clear that this ruling seeks to avoid a defence against infringement that is based on the rationale that not all independent claims of a patent referred to different inventions conforming as a whole a unity of invention are being reproduced in a product or process.

The doctrine of equivalents is not expressly contemplated by the MIPL. In fact, up to this decision, it was generally accepted by practitioners that the legal framework in Mexico required a literal approach to be taken in order to determine infringement.

According to Article 21 of the MIPL, the right conferred by a granted patent is determined by the granted claims. In turn, according to Article 12 of the same law, a claim is the essential feature of an invention for which protection is precisely and specifically claimed.

It is clear that this ruling seeks to avoid a defence against infringement that is based on the rationale that not all independent claims of a patent referred to different inventions conforming as a whole a unity of invention are being reproduced in a product or process

Based on the legal framework, only those features expressly recited in a claim are considered essential. Contrariwise, the absence of a feature should render such feature as non-essential. In other words, under this generally accepted interpretation, a product/process should be considered covered by a patent if the same contains every one and all the features of at least one patent claim. Consequently, under a literal approach, if the allegedly infringing product/process lacks at least one of the features of a claim, it cannot be considered to infringe the patent.

Regarding the interpretative nature of the claims, said Article 21 of the MIPL also states that the description and drawings present in the text of a patent shall serve to give an interpretation to the granted claims. Thus, if infringement could not be established under the literal approach based only in the wording of the granted claims, some practitioners have argued that the nature of such a feature must be analysed in view of the description and drawings in order to determine the likelihood of infringement. In this case, if accepted by a court, it was considered that this kind of equivalence analysis should be constrained to the interpretation of definitions of terms in the description and express references to functional alternatives in the same, but it would not include equivalent means or elements that were not included in the description.

However, due to the scarcity of patent litigation cases in Mexico as compared to other jurisdictions such as the US, there was a total lack of case law in this area. So until now it was not clear if a court could accept some kind of doctrine of equivalents and to what extent.

The court ruling regarding this subject asserts that, based on Article 12 of the MIPL and Article 29 of the Regulation of MIPL, it is clear that the claims of a patent have a very important role to define the scope of a patent and that the object of the law is to provide a strong protection to industrial property, as well as prevent actions that affect such exclusivity or constitute unfair competition.

Aiming to a more uniform worldwide patent system, the ruling briefly refers to other patent systems and states that a "peripheral" interpretation method of a potential cause may be confirmed the same as infringement in view of the scope of the patent, based on its claims, either by identity or equivalence.

Further, it is stated that in order to interpret the object of a patent within an administrative infringement procedure, the judge must perform an analysis in light of an expert witness opinion, whom in turn should manage the technical argot of the relevant field and deduce the actual meaning of the patented invention according to the technical context of the granted claims, instead of focusing only in the philological (i.e. literal) meaning of the used terms.

If the expert witness concludes that the allegedly infringing product/process includes all the elements recited in the granted claims, it will be understood that the claims are actually being infringed by identity. On the other hand, if the expert witness concludes that the allegedly infringing product/process is not identical to the patented invention, it would be possible to perform a further analysis to determine if the allegedly infringing product/process possesses equivalent means to the ones patented that are not identical.

The ruling goes even further, and it establishes that this peripheral method of interpretation by the expert witness should take the following into account:

1) Elements contained in the granted claims;

2) Evidence of substitution of claimed features, basing its analysis not only on prior art but also in his/her own personal knowledge;

3) The date on which the infraction is being analysed;

4) The use of equivalent elements or means that even when are substitutes of those that are claimed are excluded because they are not novel; and

5) Innovations developed after the priority or filing date of the patent.

If the expert witness, based on his/her analysis and knowledge without involving an inventive step process, reaches the conclusion that means or elements contained in an allegedly infringing product/process are different from the ones patented and that such means or elements allow such a product/process to solve the same problem that the patented invention aims to solve, then there will be an infringement of the patent in question.

Accordingly, it is clear that based on this court ruling the Circuit Collegiate Court considers that the decision about infringement must rely on the opinion of an expert witness that in turn should consider his own expertise in the technical area of the case, and must provide a broad interpretation of claimed features taking into account functionally substitute elements. In general, IP practitioners see this as a positive step in the strengthening of the patent system. However, the real impact this court ruling will have on the interpretation of claims in litigation remains to be seen.