The risk of pre-grant description amendments (T 450/20)

The EPO Boards of Appeal have recently taken an uncompromising approach to claim interpretation. The Board of Appeal decision in T 450/20 is in line with the trend, finding that the description of a patent could not be mined for a definition limiting the meaning of the claims. However, in contrast to another recent decision (T 1924/20, IPKat), the Board of Appeal in this latest case did find it permissible to use functional language from the description to construe the claims. Furthermore, in an easy to miss but critical passage, the Board also ruled out any role for the description of the patent application in claim interpretation. Instead, according to the Board of Appeal, only the description of the granted patent may be used for claim interpretation under Article 69(1) EPC, regardless of whether the description was adapted prior to grant. This is a worrying development, given the EPO's current bullish stance on the issue of description amendments, which currently necessitates patent applicants to make onerous description amendments prior to grant. 

How permanent is permanent (T 0450/20)

Stent

The decision in T 0450/20 related to EP 2254485, claiming a stent for unblocking blood vessels. The patent was upheld at Opposition. Claim 1 as granted claimed a device comprising inter alia a guide wire and a tapering mesh "permanently attached" to the wire. The feature of a tapering portion "permanently attached" to the guide wire was mentioned only once in the description and not further explicitly defined. 

The issue on appeal was whether the patent lacked novelty. The novelty of granted claim 1 depended on whether the device described in the prior art (US 2005/0209678) included an equivalent tapering portion "permanently attached" to a guide wire. The prior art device comprised a tapering portion that was firmly attached to a guide wire for the delivery of the device into the blood vessel of a patient. The prior art mentioned that the wire could be detached if necessary by applying electrical energy to a steel connecting element. However, detaching the device would be a complicated process requiring specialist equipment. The question before the Board of Appeal was primarily one of claim interpretation, particularly what did claim 1 mean by the term "permanently attached", and did it include the potentially detachable device of the prior art?

Using the description to interpret the claims

According to Article 69(1) EPC "[t]he extent of the protection conferred by a European patent or a European patent application shall be determined by the claims. Nevertheless, the description and drawings shall be used to interpret the claims." The most recent case law on claim interpretation from the Boards of Appeal has taken a hard line against using the description to interpret otherwise clear features in the claims. In both of the "catastrophic comma loss" cases (T 1473/19, T 1127/16), the patents were found invalid for added matter in view of a single comma lost from the claims (IPKat). The Boards of Appeal in both decisions found that the claims would be clear to a skilled person without recourse to the description. As such, the description could not be used to interpret the claims and rescue the claims from the added matter trap. 

In contrast to the catastrophic comma loss cases, the granted claims of the patent in T 0450/20 were not considered clear per se. Particularly, given that the claims did not define the phrase "permanently attached", it was considered unclear what this feature actually encompassed. 

Purposive construction and using the description to interpret the claims

The description of the patent did not provide an explicit definition of the phrase "permanently attached". However, the description did indicate that the device of the invention may be removed from the patient's blood vessel after it had served its purpose. The Board of Appeal thus construed the term "permanently" in claim 1 to mean that the attachment between the mesh and the guide wire must last long enough to allow reliable extraction of the mesh using the wire. The Board of Appeal therefore considered it to be acceptable to use functional language provided in the description to interpret an unclear feature of the claim.

The Patentee argued that, instead of the Board of Appeal's broad functional definition, a narrower interpretation of the phrase "permanently attached" should be used in view of the description. Particularly, the Patentee argued that a skilled person would understand from the description that "permanent attachments" did not include attachments that were releasable. Prior to grant, the patent application had in fact been amended to explicitly state that an embodiment comprising a releasable attachment was "not in accordance with the invention". The Patentee thus argued that the claims should be interpreted in view of this amended description, whereby "a releasable attachment" could not be considered a permanent attachment. 

The Board of Appeal disagreed. Particularly, citing the second catastrophic comma loss case (T 1473/19, IPKat, same Board of Appeal), the Board found that according to Article 69(1) EPC:

"only the claims determine the extent of protection. The description and the drawings have no such function, and must only be used to interpret the claims. This means that the description and the drawings can only be used for interpreting features which are already present in the claims, but not for adding further claim features or for replacing existing claim features by others". 

To the Board of Appeal, using the description to read-in a new limitation to a claim would not be in line with the primacy of the claims. The Patentee's recourse to the description to limit the meaning of "permanent" was therefore not accepted. 

The description of the patent application is irrelevant for claim interpretation

Interestingly, the Board of Appeal also rejected the Patentee's argument that the description of the application as filed may be used to interpret the claims. Before grant, the patent application in question specified an attachment that may be "releasable or permanent" (text-intended for grant). The Patentee argued that the intended meaning of a permanent attachment was therefore one that is not releasable. However, for the Board of Appeal, Article 69(1) EPC only permits the claims to be interpreted in view of the description of the granted patent, and not of the description of the patent application before grant (r. 2.16).

The Board of Appeal rejected the Patentee's argument that, because the prior art attachment was "releasable", it could therefore not be considered permanent. The purposive construction of the phrase "releasably attached" arrived at by the Board of Appeal in view of the functional language provided in the description was also found to encompass the attachment described in the prior art. Granted claim 1 was therefore found to lack novelty in view of the prior art. 

Final thoughts

There are a few interesting take home points from T 0450/20, relevant to both claim interpretation and description amendments. First, the Board of Appeal in this case found the description of a patent application irrelevant for claim interpretation under Article 69(1) EPC. According to the Board of Appeal in this case, only the description of the granted patent may be used.  Importantly however, following the recent controversial changes to the requirement to bring the description in line with the allowed claims before grant, the description of the patent may differ substantially from the description of the application as filed (IPKat). Therefore, if the approach taken in T 0450/20 is followed by other Boards, then the risk of making substantial amendments to the description prior to grant is significantly heighted. Making amendments prior to grant will not only run the risk of influencing doctrine of equivalents analysis in infringement cases, but may also adversely impact claim interpretation in any post-grant proceedings, including validity analysis at opposition. 

Second, there appears to be some divergence among the Boards of Appeal on what, if anything, may be taken from the description of a patent in order to interpret the claims. According to the latest decision T 0450/20, functional language in the description may be used to resolve a lack of clarity in the claims. This appears to contrast with another recent decision which found that functional language from the description could not be used in claim interpretation (T 1924/20, IPKat). Unfortunately, diverge in practice from the Boards of Appeal on the role of the description in claim interpretation only serve to raise the stakes in the description amendment debate. 

Further reading

Claim interpretation

• Boeing's comma drama: Commas and taking the description into account when construing a claim (T 1127/16) (12 April 2021)
• Another case of catastrophic comma loss (T 1473/19): Interpreting the claims in view of the description (16 Jan 2023)
• EPO tries to have its cake and eat it on claim interpretation (T 0169/20) (16 March 2023)
• Construing the claims to include technical effects mentioned in the description (T 1924/20) (April 2023)

Description amendments

• Board of Appeal finds no legal basis for the requirement to amend the description in line with the claims (T1989/18) (26 Dec 2021)
• Can amending the description to summarize the prior art add matter to the patent application as filed? (T 0471/20) (5 Jan 2022)
• EPO Board of Appeal toes the party-line on description amendments (T 1024/18) (4 April 2022)
• Board of Appeal case law against the description amendment requirement starts to mount up (T 2194/19) (16 Nov 2022)
• Another Board of Appeal enters the fray on description amendments (T 3097/19) (27 Nov 2022)