A seemingly straightforward narrowing amendment can have unexpected consequences after grant. T 0847/24 highlights why manufacturing claims and suitable fall-back positions should be considered well before a patent reaches opposition.
An EPO Board of Appeal decision, T 0847/24, brings into focus the risks of amending method claims post-grant to introduce a manufacturing step.
Specifically, in this case, a proprietor’s post-grant amendment added a manufacturing step to a method claim directed to configuring a physical object, but the amendment was refused even though it narrowed the method claim. This is because, under Article 64(2) EPC, the protection conferred by a process claim extends to products obtained directly by that process. The amendment in T 0847/24 brought a physical implant and surgical guide within the protection conferred by the patent for the first time.
T 0847/24 relates to EP2931143. Claim 1 of the patent as granted relates to a method for configuring a patient-specific implant and surgical guide for maxillofacial surgery. In the method, a 3D model of the patient’s anatomy is generated, an osteotomy is simulated, and 3D structures for the implant and the surgical guide are determined. Importantly, the claim of the granted patent did not include a step of manufacturing anything. The patent was opposed and the opponent argued, successfully, that the claims lacked inventive step because the only distinguishing feature (determining the 3D structure of the implant) was a simulation that lacked technical character. The Opposition Division revoked the patent due to a lack of inventive step, and the proprietor appealed.
During the opposition appeal proceedings, the Board of Appeal agreed that claim 1 of the proprietor’s main request lacked inventive step. The Board noted it was common ground that determining the 3D structure of the implant was non-technical when considered in isolation, since it merely corresponded to the generation of abstract data representing a 3D structure. Following G 1/19, the Board held that the feature could only contribute to the technical character of the method claim if a technical use of the simulation data was at least implicitly specified in the claim. While manufacturing an implant was a possible, or even highly likely, use of the resultant data, that was not enough to confer technical character. The claim was directed to configuring an implant rather than making it, and the data was not adapted for a particular manufacturing apparatus (such as a 3D printer). Therefore, non-technical uses (e.g., a user comparing the determined design with an off-the-shelf implant) of the data were not excluded from the claim and could be realistically envisaged. This is a fairly typical application of the EPO’s assessment of computer-implemented inventions under G 1/19, where claims to simulations that do not provide a tangible output sometimes face an uphill battle.
The proprietor had filed an auxiliary request in which claim 1 was amended to include an additional step of “producing the surgical guide and the implant”. It was undisputed between the parties that this seemingly simple amendment would lead to a clear technical effect and address the technical character problems, by providing a direct link between the method and physical reality. The amendment clearly limits the literal scope of the method claim and appears, at first glance, to satisfy Article 123(3) EPC, which specifies that: “The European patent may not be amended in such a way as to extend the protection it confers”. Indeed, the Board accepted that the method defined by the amended claim fell within the scope of claim 1 as granted.
The opponent argued that this amendment broadened the protection provided by the patent in breach of Article 123(3) EPC and the Board ultimately agreed. Its reasoning was that the assessment of whether an amendment satisfies Article 123(3) EPC must also take Article 64(2) EPC into account. Under Article 64(2) EPC, the protection conferred by the patent included not only the method defined by the granted claims, but also products directly obtained by the method: “If the subject-matter of the European patent is a process, the protection conferred by the patent shall extend to the products directly obtained by such process”.
Before the amendment to include a manufacturing step, the direct product of the patented method was data defining a configured implant and surgical guide. The Board accepted that a physical medium storing that data might also be a direct product of the method claim (citing the German Federal Court of Justice, MPEG-2-Videosignalcodierung, X ZR 33/10), but a physical implant was far removed from the data defining it. A physical implant was therefore not directly obtained by the granted method claim, which merely produced data. Following the amendment, the direct products of the patented method were a physical implant and surgical guide, so the Board held that the amendment would extend the protection conferred by the patent to products that were not protected by the unamended patent, violating Article 123(3) EPC. The proposed amendment was therefore refused.
Since the remaining auxiliary requests were also refused for a lack of inventive step, the appeal was dismissed and the patent revoked.
The headnote of the decision sets out the Board’s conclusions succinctly:
“If a granted claim defines a computer-implemented method for configuring a physical object which, when carried out, merely results in data representing that physical object, and not in the object itself, amending the claim such that it additionally includes the step of manufacturing the physical object so configured is, in view of Article 64(2) EPC, not allowable under Article 123(3) EPC (Reasons 6).”
Practice points
Where the disclosure supports it, best practice is to pursue claims to a physical product itself as well as to a method of manufacturing it, so that the product as such is protected by the claims as granted. Relying on a post-grant amendment to convert a simulation method claim into a method of manufacturing an article may therefore be problematic.
In cases where calculations or simulations are performed, proprietors should not assume they can add a manufacturing step post-grant. Proprietors should consider during prosecution whether a manufacturing step might need to be added to credibly argue that the claims provide a technical effect. In such cases, it may be worth including a dependent claim with a manufacturing step. If a dependent claim to a method of manufacturing is granted, the physical product would arguably then be within the protection conferred by the patent under Article 64(2) EPC, so it would seem that incorporating the manufacturing step into the independent claim later should not lead to any extension of the protection.
An amendment to add a manufacturing step to a method claim will always need basis in the application as originally filed, so this issue should be addressed at the drafting stage. Include layered fall-back positions of increasing specificity to provide basis for progressively more specific methods.
If a method claim including a manufacturing step is not commercially useful (for example, because the manufacturing step occurs outside Europe), consider whether the output of the method can be defined in a way that implies a specific technical use. For example, a claim directed to producing data formatted to be directly usable by a particular manufacturing apparatus (e.g., a 3D printer), or data containing machine-readable instructions for the manufacturing of a physical object, may have a better prospect of being allowed. The Board indicated that a limitation of this kind might have implied a technical use of the data.
This case does not raise entirely new legal issues, since similar problems have arisen from changes of claim categories in other fields. For example, T 1635/09 recognised the potential interplay between Articles 123(3) and 64(2) EPC in the context of use and process claims for oral contraceptive compositions, and the Board in T 0847/24 referred to this earlier case when holding that Article 64(2) EPC must be taken into account under Article 123(3) EPC. Moreover, the issue is also not confined to the EPO, since extension of protection is a ground of revocation before national courts and the UPC. Therefore, the same trap can apply to post-grant amendments there as well.
The practical question is whether key applications contain sufficient fall-back positions before they are needed. Now may be a good time to review strategically important portfolios with this in mind.
Rhodri Kendrick
This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.
© Withers & Rogers LLP October 2026
