Pursuant to Article 138(3) of the European Patent Convention (EPC), a patent proprietor is entitled to limit the patent by amending the claims in proceedings before the competent court or authority relating to the validity of the European patent. According to the same provision, the patent, as limited, shall form the basis of the proceedings.
At the same time, under the Turkish Industrial Property Code (Law No. 6769), patent validity is, in principle, assessed based on the claims as granted. The interaction between these two frameworks creates a practical question: whether and to what extent Turkish courts may consider amended claims submitted before the Turkish Patent and Trademark Office (TURKPATENT) for a European patent validated in Turkey (officially Türkiye), after the initiation of invalidation proceedings before the Turkish courts.
A recent dispute offers a clear practical answer.
Background to the case
In an invalidation action brought by a generic company, initial expert reports indicated that the patent faced a serious risk of revocation in its granted form. As the case progressed, the patent proprietor limited the claims in parallel with proceedings before the EPO, had these amendments filed before TURKPATENT, and submitted them to the court.
Following the acceptance of the claim limitation request by TURKPATENT, the Intellectual and Industrial Property Court (the IP Court) ordered an expert report to assess whether any grounds for invalidation existed, taking into account the amended set of claims. Although the experts had previously opined in their report that the patent should be invalidated based on the original set of claims, they subsequently concluded that the limited set of claims did not contain grounds for invalidation.
In this context, the IP Court was requested to render its decision accordingly, it being emphasised that Article 138(3) of the EPC clearly grants the patent proprietor the right to amend the claims of a European patent, and that, in such circumstances, the national court must assess the invalidation allegations of the disputed patent on the basis of the final amended version of the claims.
The plaintiff objected to the consideration of these amendments, arguing that the invalidation assessment should be carried out with the claims as they existed at the time of filing of the invalidation action. According to the plaintiff’s argument, allowing amendments at a later stage would undermine procedural certainty and adversely affect the position of the plaintiff.
The ruling and its implications
Despite the plaintiff’s objections, the IP Court and the Regional Court of Appeal assessed the patent based on the amended claim set and ultimately dismissed the invalidation action. This approach indicates that Turkish courts would – as they should – consider claim amendments submitted as per Article 138(3) of the EPC during the proceedings when assessing an invalidation action.
This practice highlights a crucial point: the right to limit a patent by amending its claims under Article 138(3) of the EPC is far from merely theoretical—it produces concrete and meaningful procedural consequences in Turkish litigation. In the authors’ view, considering the functional relationship between the right to limitation under the EPC and the national invalidation procedure, claim amendments submitted under Article 138(3) of the EPC should be regarded as an important part of the patent proprietor’s defence. Accordingly, Turkish courts should continue to assess patent validity based on the amended claims.
Indeed, the interaction between Article 138(3) of the EPC and the Turkish invalidation framework demonstrates that claim amendments are not a merely procedural formality but a substantive mechanism capable of directly influencing the outcome of patent disputes in Türkiye. The examined case makes clear that Turkish courts are willing to take into account post-grant claim limitations accepted by TURKPATENT and to reassess patent validity on the basis of the amended claims, even where earlier expert opinions pointed towards invalidation.
This approach reflects a pragmatic and harmonised interpretation of the EPC within the Turkish legal system. By recognising amended claims as the operative basis of the dispute, courts ensure that the patent is evaluated in its legally valid and current form, rather than being confined to an outdated version that no longer reflects the scope of protection sought by the proprietor.
From a strategic standpoint, this practice reinforces the importance of Article 138(3) of the EPC as a key defensive tool in invalidation proceedings. Patent proprietors should therefore carefully consider timely claim limitation—whether before the EPO or TURKPATENT—as part of their litigation strategy.
