Lack of regulation on plausibility attacks in Turkish patent law

The grounds for the invalidation of a patent within the scope of Turkish Industrial Property Law No. 6769 are listed as per the numerus clausus principle. The concept of plausibility – which has been the subject of numerous evaluations, especially by the EPO, and frequently debated in academic circles in recent years – has not yet found a place within the scope of any legal regulation in Turkey. Moreover, there is no consensus on the Turkish word that meets this concept as a legal term.

However, the concept of plausibility has started to be argued by the plaintiffs in Turkish invalidity proceedings and been the subject of important conclusions by the EPO Enlarged Board of Appeal within the scope of application No. G 2/21, so the place of the concept of plausibility in Turkish legal practice must be examined carefully.

The requirement of plausibility is particularly an issue with regard to pharmaceutical patents, because all the test data of clinical studies may not be obtained by the date of the patent application due to the long duration of efficacy tests and their sophistication.

Therefore, considering the necessity of making a patent application as soon as possible to avoid any loss of rights, there are issues around how much of the research on inventions should be included in the patent application and to what extent post-published evidence can be used.

Plausibility can be defined as the ability to demonstrate the technical effect claimed by the invention in a credible and convincing manner with appropriate evidence to be submitted, or to deduce this situation from the state of the art or common general knowledge, to avoid speculative patents that can be produced at the desk (Türk Patent Hukuku, Uğur Çolak, Adalet Yayınevi, Ankara, 2022; A Practitioner’s Guide to European Patent Law, Paul England, Hart Publishing, London, 2019).

In other words, the concept of plausibility can be regarded primarily as a prohibition of speculative patent applications which do not clearly disclose a technical effect of a chemical substance and/or disclose a technical effect which is not normally expected.

Although this requirement is not one of the invalidation grounds stipulated in Turkish legislation, or in the Agreement on Trade-Related Aspects of Intellectual Property Rights or the European Patent Convention, to which Turkey is a party, it can be subject to invalidity examinations by asserting in the context of sufficiency of disclosure or inventive step.

Indeed, where the concept of plausibility has been used as an argument before the Turkish intellectual and industrial rights law courts, the allegations on this issue were included under both headings.

The issue of plausibility is also associated with inventive step and sufficiency of disclosure in the case law created before the EPO. Given that "credible" was used instead of "plausible" in Case T 939/92 (AgrEvo), there are opinions claiming that this decision, which concluded that a technical effect should be reasonably predictable and credible, was the first to use the threshold of plausibility, as well as the opposite of these views in the doctrine.

According to these contrary views, Case T 1329/04 (John Hopkins) was the first to establish the plausibility threshold, in explaining that it was at least made plausible that the claimed invention could be carried out.

In contrast to these cases, Case T 609/02 (Salk) concerned the plausibility threshold in relation to sufficiency of disclosure and it was concluded that there was the requirement to make the existence of a cause and effect relationship plausible.

Finally, in a more recent case, T 488/16 (Dasatinib/BRISTOL-MYERS SQUIBB), the EPO Enlarged Board of Appeal clarified that even though there is not always a requirement to have experimental data in an application, the technical problem must at least have been shown to be plausibly solved at the filing date.

The plausibility issue also raises a discussion regarding filing post-published documents. There are many EPO T decisions (see, in particular, T 578/06) addressing the plausibility issue together with post-published evidence. The majority of the decisions stress that post-published evidence can be considered on the condition that a certain effect was plausible at the filing date of the patent application. In that situation, post-published documents can be accepted.

However, given that the concept of plausibility is only just gaining currency in Turkish law and that it has not been put forward as a sound argument by plaintiff parties, it has not yet been included in any high court case law and has not been evaluated in any decision by a court of first instance.

Indeed, the plaintiff claimed in a recent patent invalidation action that the subject patent was not plausible in the context of insufficient disclosure, but the plausibility requirement was erroneously defined because of the presence of all the evidence in the patent document that directly and undoubtedly proved that the technical problem had been resolved.

However, according to the EPO’s practices, for example, the submission of in vitro test results may be sufficient to make the solution of the technical problem foreseen in the patent plausible. In this respect, given that it was obvious that the plaintiff could not prove its claim in accordance with the general principles of the law of proof, the court of first instance concluded that the invention was fully and sufficiently disclosed to allow the implementation of the invention by the technical expert. No evaluation was made regarding the plaintiff’s plausibility argument; therefore, no steps were taken to form case law on plausibility.

At the point reached in the practice of Turkish intellectual property law today, it is not possible to talk about advanced plausibility arguments having been put forward, or argue that case law that can be used as a criterion in the plausibility evaluations to be made by the courts has been established.

However, the decision to be issued regarding the G 2/21 application by the EPO Enlarged Board of Appeal following the oral hearing held on November 24 2022, which is expected to bring about important standards regarding the requirement of plausibility and which addresses important questions about whether post-published documents should be taken into account in the examination of plausibility, will have great repercussions in the patent world. It would not be wrong to say that the effects of this decision will be seen in Turkey as well.

While there is no case law that can be taken as a precedent in Turkish legal practice, in the opinion of Gün + Partners, and given that Turkey is a party to the European Patent Convention, the G 2/21 decision will help to establish a uniform approach to applications by constituting a direct precedent for Turkish patent law.

The industry is very excited to see the written decision of the EPO Enlarged Board of Appeal, which will bring enlightenment to pending disputes in different types of jurisdictions.