T 1762/21 and intermediate generalisation before the European Patent Office

A ruling by the European Patent Office’s Board of Appeal has clarified the allowability of amended claims via ‘intermediate generalisation’. Martin Kohrs outlines the decision and what it means in practice. 

Decision T 1762/21 by a Board of Appeal of the European Patent Office (EPO) concerns the allowability of amended claims in which certain features originally present have been deleted and the basis for such amendments in the application as filed. The decision clarifies a topic well known to applicants and their representatives, that of ‘intermediate generalisation’, which refers to subject-matter falling between a particular embodiment and the definition of the invention in general terms, both of which are defined in the application as filed. This is common when an attempt is made to clarify an independent claim by means of a feature taken from an embodiment, when that example has other features.  

Intermediate generalisation and Article 123(2), EPC 

In the case of amendments to the claims in particular, Article 123(2) of the European Patent Convention (EPC) lays down a strong requirement which is strictly applied by the EPO, namely that: 'The European patent application or patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed.' 

This rule, which has been repeatedly confirmed by case law, is that an amendment is permissible, from the point of view of Article 123(2), only if the amendments is made ‘within the limits of what a skilled person would derive directly and unambiguously, using common general knowledge, and seen objectively and relate to the date of filing, from the whole of [the] documents as filed’.  

To determine whether a feature can be extracted from a particular embodiment and added to the claim, the EPO's Examination Guidelines require that: 

• The characteristic is not related or inextricably linked to the other features of that embodiment, and 
• The general disclosure justifies the isolation of the feature, leading to a generalisation, and its introduction into the claim. 

Background to decision T 1762/21 

The decision concerns an appeal against a ruling by the Opposition Division. Both the latter and the Board of Appeal decided to maintain the patent as granted.  

The patent relates to a breast tomography system, a three-dimensional (3D) medical imaging technology in which X-ray images are obtained by a detector with multiple viewing angles, with an X-ray tube moving between each shot. An anode, cathode and port define a focal point of the X-ray tube. The X-ray images can then be processed to obtain high-resolution sections. The invention is intended to synchronise the displacement of the X-ray tube with a displacement of the 'static' focal point of these rays, to maintain a substantially fixed 'effective' focal point during the exposure time. This makes it possible to reduce both the length of the exposure period and blurring in the images.  

During the examination proceedings, the applicant had amended the claims on several occasions, introducing features from the description. The opponent had argued that the extraction of these features from the description was an intermediate generalisation, as other features of the description had been omitted.  

For example, the applicant had included in the claim a reference to compression vanes (but without mentioning that these vanes were 'lower and upper' vanes) and a reference to an anode (but without mentioning that the anode was mounted on a shaft driven by a motor).  

According to the opponent, it would also have been necessary to integrate a filter, a collimator and a vacuum glass tube, as well as the definition of the shape of the cathode and that of a focusing cup. 

Board of Appeal decision 

The Board of Appeal rejected these arguments, recalling the well-known rules referenced earlier, and stating the following in point 2.5 of its decision: 

‘Features in the description concerned with other aspects of the system, such as the way the x-rays are generated or the way the breast is fixed in place on the detector, may be left out of the claims as long as they are not relevant to the optimisation, even if they contribute to the general functioning of the tomosynthesis system... The person skilled in the art would have recognised that the omitted features do not contribute to optimisation of the acquired images by acting on the focal spot.’ 

According to the decision, it would be possible, therefore, under certain conditions: 

• to supplement a claim with certain features of an embodiment, while omitting those which do not contribute to the result to be obtained; and 
• for features which do not contribute to the result to be obtained, to incorporate them into the claim without adding to them the qualifiers to which those features are associated in the embodiment example.  

Applying the decision in practice 

The decision brings interesting nuances in the application of intermediate generalisation rules. In particular, it challenges the idea that the extraction of a feature from an embodiment example to include it in a claim would also require the remainder of the embodiment example to be integrated word for word. 

For additional guidance on intermediate generalisation or support filing and prosecuting patents at the EPO, speak to your Novagraaf attorney or contact us below.  

Martin Kohrs is a French and European Patent Attorney based at Novagraaf in Paris.