In a recent decision, T 1762/21, the Board of Appeal considered how intermediate generalisations should be assessed for added matter. The decision provides some clarity on when features are – or are not – inextricably linked to other features disclosed in an embodiment.
Added matter and intermediate generalisations
As many applicants will be aware, the European Patent Office (EPO) adopts a relatively strict stance when it comes to the assessment of claim amendments for added matter under Article 123(2) EPC. The “gold standard” for compliance under Article 123(2) EPC is that the claimed subject matter must be directly and unambiguously disclosed in the application as filed, taking into account the common general knowledge of the skilled person at the time of filing (G 2/10).
It is well established that extracting a specific feature from an originally disclosed combination of features, and using it to delimit claimed subject matter, may only be allowed if there is no structural and functional relationship between the features. When a feature is taken from a particular embodiment and added to a claim, it has to be established i) that it is not related or inextricably linked to the other features of that embodiment and ii) that the overall disclosure justifies its isolation and introduction into the claim (Guidelines H-V.3.2.1). If these criteria are not met, i.e., if a feature is inextricably linked to others that have been omitted from the claim, the amendment would represent an unallowable ‘intermediate generalisation’. Such a claim would add matter under Article 123(2) EPC.
Background
The case concerns EP2352431B1 (Hologic, Inc.), which relates to a breast tomosynthesis system. Tomosynthesis is an imaging system that can be used to screen for early signs of breast cancer. It uses X-rays to obtain sectional images of the breast from multiple angles, which are then reconstructed to create a 3D image. It is performed by moving an X-ray tube on a circular arch and making a series of low-dose exposures.
In conventional X-ray tubes the focal spot is static relative to the tube. As the X-ray source continuously moves through space during each exposure period, the focal spot also moves. This focal spot movement causes image blurring and reduced diagnostic accuracy. The invention as claimed aimed to provide improved image clarity in the presence of the moving X-ray source by modifying focal spot characteristics.
Claim 1 as originally filed related to the X-ray tube itself. However, the claim was amended during prosecution to relate to a breast tomosynthesis system comprising the X-ray tube of original claim 1. The Opponent, Siemens Healthcare GmbH, argued that the claims as granted added matter because several features essential for the whole system had been inadmissibly omitted. For example, they asserted that the relevant embodiment provided in the description includes features such as a scatter grid, “upper and lower” compression paddles, the anode being mounted on a shaft and rotated by a motor, a filter, and a collimator, none of which are defined in claim 1. This amounted, in their view, to an unallowable intermediate generalisation.
As a consequence of the omission of these features, the Opponent further argued that embodiments other than those disclosed in the application as filed fell under the scope of protection.
Decision
The Board of Appeal disagreed with the Opponent, concluding that the claims did not add matter.
The Board reasoned that whilst the omitted features may contribute to the general functioning of the tomosynthesis system, they are not necessary for achieving the effect of optimising acquired images by acting on the focal spot. In this regard, the Board stated that:
“the features of these claims relate specifically to optimising the acquired images by acting on the focal spot. 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” (emphasis added)
and, further, that:
“the omission of a scatter grid, of the qualification of “upper and lower” for the compression paddles, of the anode being mounted on a shaft and rotated by a motor, of a filter, of a collimator, of a glass vacuum tube, of the cathode in the form of a heated filament and of the form of the focusing cup… is not problematic. 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…. The person skilled in the art would have been aware of several alternative mechanical arrangements for such control and is thus not presented with technical information which was not directly and unambiguously derivable from the application as filed” (emphasis added)
The appeal was therefore dismissed, and patent was maintained as granted.
On the Opponent’s argument that embodiments other than those disclosed in the application as filed fall under the scope of protection, the Board noted that this was of no relevance. Unlike Article 123(3) EPC, which concerns post-grant amendments and requires that the patent may not be amended so as to extend the scope of protection it confers, Article 123(2) EPC is not concerned with scope of protection. Instead, it concerns the “comparison of the information linked to the amendment under scrutiny with the information directly and unambiguously derivable from the application as originally filed”.
Conclusion
The decision is in line with established practice that a specific feature can only be extracted from a disclosed embodiment and added to a claim under certain circumstances. However, it has provided some clarification as the circumstances under which a particular feature is deemed to be “inextricably linked” to others.
In this case, the Board found that the omitted features were not necessary – or essential – for optimising the acquired images by acting on the focal spot. In fact, the skilled person would know that alternative mechanical arrangements could be used to achieve this effect. As such, when taking into account the common general knowledge of the skilled person at the time of filing, the subject matter as claimed could directly and unambiguously be derived from the application as filed. Conversely, in cases where the omitted features are necessary for achieving the effect associated with the added features, it follows that the amended claim would convey technical teaching that is in contrast with, and extends beyond, the original disclosure. This is because the skilled person would incorrectly take from the claims that the effect can be obtained without the omitted features.
Although the decision may provide some comfort to Applicants that non-essential features of an originally disclosed embodiment may be left out of a claim, particularly where there are known alternatives, care must still be taken when making amendments at the EPO. Indeed, the “gold standard” that any introduced subject matter must be directly and unambiguously derivable from the application as filed, taking into account the common general knowledge at the time of filing, still applies.
