CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 426/22 – Inserting “preferably” in a claim does not necessarily infringe Art 123(2)

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Brief outline of the case

The OD decided that the MR was infringing Art 123(2) and maintained the patent according AR1.

The proprietor appealed.

The board found that the MR did not infringe Art 123(2) and decided to remit the case for further prosecution.

The features at sake

Claim 1 (apparatus) of the MR comprised, inter alia, the following features:

  • The apparatus was qualified as ski slope groomer and not more generally as crawler machine.  
  • F1.A an accessory assembly (11) comprising a tiller (12) and a blade (13), and preferably a winch (14);
  • F1.B2 preferably the ski slope groomer (1) comprising a fourth electric machine 5 (34) is connected electrically to the electric transmission line (35), and mechanically to winch (14) to transfer kinetic energy to winch (14).”

Claim 15 (method) comprised corresponding features.

The opponent’s point of view

In accordance with the reasoning of the OD, the opponent maintained that the introduction of the term “preferably” in features F1.A and F1.B2 of claim 1, which rendered the provision of the winch and of the fourth electric machine associated thereto merely optional, resulted in an undisclosed and hence unallowable intermediate generalisation of the only specific embodiment of the ski slope groomer described in the originally filed application which unambiguously comprised an accessory assembly including a tiller, a blade and a winch in combination.

For the opponent, whilst the accessory assembly and hence any of its components including the winch could be considered optional when looking at the original claim directed to a generic “crawler vehicle”, it was unfounded when referred to a “ski slope groomer” to which claim 1 was restricted.

For the opponent, a ski slope groomer, if deprived of the accessories at issue, was not able to carry out its intended and main functionality, namely to prepare and make safe a ski slope for the skiers. In other words this result could not be achieved without providing the optional winch.  

The proprietor’s point of view

The proprietor essentially argued that for a skilled reader the fact that independent claims 1 and 15 were amended to recite that the accessory assembly (11) of the claimed ski slope groomer “preferably” comprised a winch (14) (feature F1.A) operated by a fourth electric machine (34) associated thereto (feature F1.B2) did not result in an unallowable intermediate generalisation infringing Art 123(2).

The board’s decision

It was uncontested that the originally filed application explicitly disclosed a ski slope groomer comprising an accessory assembly (1) in turn comprising in combination a tiller (12), a blade (13) and a winch (14).

It was also uncontested that the application as originally filed did not contain any explicit indication that the winch (or any other accessory) and the associated electric machine (34) are optional/preferred features.

The board took the view that, according to common understanding the term “accessory” is indeed generally used to qualify an item which might be additionally and optionally provided on a main item as an add-on element.

Therefore, the expression “accessory assembly” inherently contains the indication that the assembly represents an optional feature of the disclosed sky slope groomer and therefore that any or all of its disclosed components, namely the tiller, the blade and the winch can be omitted.

The Board could not see any reason why, should an “accessory assembly” be always required to carry out the functionality intended for this kind of vehicle, it must mandatorily include all three accessories presented in combination in the description and in particular a winch.

For example a ski slope groomer comprising a tiller and a blade would be perfectly able to carry out at least some of the expected functionalities, i.e. preparing a ski slope even in absence of a winch.

The Board thus shared the view of the proprietor, that an expert in the technical field of the design and operation of ski slope groomers reading the application as filed in the light of common general knowledge is aware that the decision of whether the sky slope groomer must be equipped with an accessory assembly and – should this be the case – which specific accessories must be provided, only depends on the expected operation requirements.

Further, the board concurs with the view of the appellant (patent proprietor) that – contrary to the allegation of the opponent – the winch and the fourth electric machine associated thereto are not inextricably and functionally linked to any other features of the disclosed sky slope groomer, in particular to the presence of the tiller and/or the blade.

In fact, the board had no doubt that these two accessories could indeed be provided and operated (or not) irrespective of the presence of the winch which does not have any decisive relevance when flattening and preparing the sky slope has to be carried out. The winch (14) and the associated fourth electric machine (34) can be removed from the ski slope groomer without essentially modifying the basic structure and drive of the machine or being detrimental to its capability to operate only with the blade and the tiller installed.

The expression “preferably” introduced in features F1.A and F1.B2 of claim 1 and in features F15.A and F15.B2 of claim 15 according to the MR does not result in any unallowable intermediate generalisation of the specific embodiment presented in the description.


It can be agree with the board when it considers that any implement qualified as accessory can be considered optional.

When it comes to the tiller and the blade on a ski slope groomer, doubts are permitted.

Irrespective of the date, but I am convinced that a timely published document can be found, Wikipedia generally defines a ski slope groomer as comprising front mounted, blades and powered rotary tillers. Snow groomers can handle very steep gradients due to their low centre of gravity and large contact area, but they can also be assisted by winches.

It was thus wise for the proprietor to limit the optional character to a winch.

As far as the blade and the tiller are concerned, the opponent had a point.

Although the boards do proscribe its use, the “three point test”, Guidelines H-V, 3.1 could have been used by the OD. It comes to the same result and corresponds to the “golden standard”.


3 replies on “T 426/22 – Inserting “preferably” in a claim does not necessarily infringe Art 123(2)”

francis hagelsays:

Dear Mr Thomas,

This decision reflects a surprisingly lenient approach of art 123(2).

The addition of the term « preferably » is clearly a substantial change. An explicit declaration that a feature is only optional, when this was not explicit in the original application, cannot be equated to the conclusion of the type of reasoning as used by the Board, which I find difficult to call « unambiguous », especially because it requires the common general knowledge of the skilled person.

And even though this can be « derived » by reasoning, the addition of « preferable » is a strong shift of emphasis, which is new matter in its own right.


Dear Mr Hagel,

Thanks for your comment.

I do agree with you that the present decision reflects a surprisingly lenient approach of Art 123(2). This is the more so, since the feature of a winch was by no way declared optional in the original disclosure.

It has to be noted that the accessory assembly (11) comprising a tiller (12), a blade (13), and a winch (14), is not a unit/assembly on its own and the elements of that “accessory assembly”, are disposed at various places on the slope groomer.

The tiller (12) is disposed at the back of the ski slope groomer, the blade (13) at the front of the ski slope groomer and the winch (14) is completely separate from the two other accessories and is positioned on top of the rear part of the ski slope groomer.

In view of the position of the winch it is highly doubtful that it can be “preferably” driven by anything else than an electric motor.

Normally the winch on a ski slope groomer is situated at the front of the groomer as it is meant to help it climb relatively steep slopes. This is not the case of the present ski slope groomer.

Other boards would have been more reluctant to accept such an amendment. The present decision might well remain a one off.

I do not think that this decision is in coherence with the strict line adopted by the EBA and the oter boards when it comes to added matter.

francis hagelsays:

Dear Anonymous,

My comment was somehow based on “guts feeling”. The perception and meaning of a shift of emphasis are subjective. Thus I feel lucky that your thorough analysis clearly supports my comment.

I agree with you that the case law and the practice of the EPO should not depart from a strict approach regarding the qualifications expressed by the applicant in the original application to the different elements disclosed in the application, whether they are “preferred” or “preferable”, “essential” or “optional”. Such qualifications must be taken seriously. After all, the applicant chooses every word of the original application.

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