T 0190/99 - Claims read by a "mind willing to understand" - #41

Citation rank: 41
No. of citations: 109

T 190/99 is famous for its statement that a patent claim must be "construed by a mind willing to understand not a mind desirous of misunderstanding" (cf. Headnote).

In the underlying appeal case the proprietor has amended claim 1 such that, if the original wording of claim 1 was interpreted literally, the amendment could be seen as extending the protection conferred over the one of the granted patent (Art. 123(3) EPC).

The invention related to a woven slide fastener, which included, i.a., "a plurality of binding warp threads (17, 18)", and "a plurality of tensioning warp threads (19)".

Original claim 1 required i.a.:

"the plurality of tensioning warp threads (19) extending parallel with and between said upper and lower binding warp threads (17, 18)".

When looking at the figures and the description (in particular Fig. 2 of the patent), it was immediately apparent that the tensioning warp threads 19 did not extend strictly parallel with (and between) the upper and lower binding warp threads 17, 18, as claimed. Instead, the tensioning warp threads 19 were arranged in some sort of a zig-zag pattern between parallel upper and lower binding warp threads 17 and 18.

Fig.2 of the patent (ref. numeral 19 added)

The patentee had filed an amendment by which the above claim feature was replaced by the following:

"each said tensioning warp thread (19) extending between adjacent upper binding warp threads (17,17) and between adjacent lower binding warp threads (18,18) in a plane parallel to planes in which the upper and lower binding warp threads (17,18) are disposed"

The appellant-opponent argued that the original claim feature unequivocally required parallel tensioning warp threads 19. The amended claim feature, however, now included embodiments in which the tensioning warp threads 19 were not strictly parallel to the upper and lower binding warp threads 17, 18, e.g., the feature now also covered the zig-zag pattern of the tensioning warp threads shown in Fig. 2. Art. 123(3) EPC would thus be infringed.

The Board, however, took a different stance. They considered that the literal interpretation of the original claim feature made little sense. They stated:

"2.2.3. It is of course part of the most basic knowledge of the skilled person that, in order to weave a fabric, the warp threads are arranged parallel to each other prior to inserting the weft thread. However in the finished fabric, e.g. a conventional plain weave fabric, each warp thread goes over one weft thread and under the next weft thread and so on. While the warp threads still appear to be parallel when the fabric is seen in plan, in cross section the warp threads can be seen to be running approximately sinusoidally in order to lock the warp and weft threads together. Thus the warp threads are not parallel in the strict sense of being equidistant straight lines.

2.2.4. Thus the skilled person, reading in claim 1 as granted that the tensioning [...] threads 19 [...] extend parallel with the upper and lower binding warp threads 17 and 18, would not unreservedly assume that "parallel" meant "parallel" in the strict geometrical sense of the word."

The skilled person would bear the description and drawings of the patent in mind when deciding what claim 1 as granted means. He would not adhere to the strict literal wording of the claim. Instead, he would would interpret the claim wording so that it makes sense:

"2.4. The board adds that the skilled person when considering a claim should rule out interpretations which are illogical or which do not make technical sense. He should try, with synthetical propensity i.e. building up rather than tearing down, to arrive at an interpretation of the claim which is technically sensible and takes into account the whole disclosure of the patent (Article 69 EPC). The patent must be construed by a mind willing to understand not a mind desirous of misunderstanding."

Applying these principles of interpretation, the amendment requested by the patentee was found not to infringe Art. 123(3) EPC.

The appeal was dismissed.

Remark: T 190/99 is sometimes used by applicants in response to clarity objections; the argument being that a "mind willing to understand" would be able to make sense of the claim wording, thus Art. 84 would not be infringed. I find that a distinction must be made between opposition cases (in which the possibilities of amending a claim are restricted Art. 123(3) EPC and cannot be contested under clarity, and examination proceedings (in which the claim language can be changed more freely). The Headnote of T 190/90 should not be over-streched and used as a justification for unclear or inconsistent claims upon examination.

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Headnote:

The skilled person when considering a claim should rule out interpretations which are illogical or which do not make technical sense. He should try, with synthetical propensity i.e. building up rather than tearing down, to arrive at an interpretation of the claim which is technically sensible and takes into account the whole disclosure of the patent (Article 69 EPC). The patent must be construed by a mind willing to understand not a mind desirous of misunderstanding. 

The full text of the decision can be accessed here.

Quotes from 10 random decisions citing T 190/99 can be found here.