EPO Enlarged Board Of Appeal - The Definition Of "Inconsistency"

As we've previously reported here and here, the Enlarged Board of Appeal (EBA) at the EPO has been grappling with a big question in case G 1/25: when you amend the claims of a patent or patent application, do you also have to amend the description to match? This has been a hot topic - especially among European Patent Attorneys - with strong views on both sides. Some see it as essential for making sure third parties know exactly what a patent covers. Others think it's a pointless exercise that wastes time and money, and can actually do more harm than good.

Well, the EBA has now handed down its decision, and for those in the latter camp the headline is good news. The old EPO practice of demanding full correspondence between description and claims has been dialled back. Going forward, you'll only need to amend the description if there's an "inconsistency" between the claims and the description - and the EBA has given that term a specific, and fairly narrow, definition. On the face of it, that's a relief for most EPO users, though of course the proof of the pudding will be in how the various EPO departments actually apply G 1/25 in practice. Here's the full picture:

The referral questions

G 1/25 started life as a referral from Technical Board of Appeal 3.3.02 in case T 0697/22. The underlying patent (No. 2124521, "Hydroponics Growing Medium") had Knauf Insulation as proprietor and ROCKWOOL A/S as opponent. The Board spotted two contradictory lines of case law on whether amending the claims means you also have to tidy up the description, and referred three questions to the EBA:

1. Whether it is necessary to adapt the description when a claim amendment introduces an inconsistency between the amended claims and the description.
2. If so, which which EPC requirement(s) mandate that adaptation.
3. Whether the answers differ between examination proceedings and opposition proceedings.

The two diverging lines of case law

The first line of case law said yes - the EPC does require the description to be consistent with amended claims.

The second line, championed most notably in T 56/21, took the opposite view. It treated Article 84 EPC as a "one-way street": the claims have to be supported by the description, but that obligation doesn't work in reverse. So a patent cannot be refused just because the description doesn't match the amended claims. These decisions also said claims should be assessed for clarity on their own terms, without looking at the description.

What the EBA decided

Building on G 1/24

The EBA's reasoning leans heavily on its earlier decision in G 1/24, which established that the description and drawings must always be considered when interpreting claims - not just when a claim seems unclear in isolation. Claim interpretation is a "holistic" exercise: the claims, description, and drawings are read together as a package. That said, the description and drawings can shed light on what the claims mean, but they can't be used to stretch or shrink the claims beyond what the wording actually supports.

Rejection of the second line of case law

The EBA rejected the second line of case law (T 1989/18, T 2194/19, T 1444/20, and T 56/21) outright. Those decisions were built on the idea that Article 84 EPC is only about the claims and that you assess clarity without looking at the description. After G 1/24, that premise simply doesn't hold up anymore. A straightforward reading of Article 84 EPC doesn't support the "one-way street" theory - you can't just ignore the description when inconsistencies muddy the waters around what the claims actually mean.

What counts as an "inconsistency"?

The EBA came up with a specific definition: an "inconsistency" exists where the description (or drawings) suggests a reading of a claim that clashes with what the claim appears to mean, and that clash can't easily be sorted out using the interpretive principles from G 1/24.

Crucially, it's not an inconsistency just because the description mentions embodiments or examples that fall outside the scope of the claims. Thus, it is not necessary to strip out every bit of unclaimed subject-matter from the description.

No need for a full "clean-up"

Article 84 EPC doesn't demand a perfect match between description and claims, and there's no general obligation to scrub the description of anything not reflected in the claims. The EPC doesn't require adaptation of the description just for the sake of tidiness.

So when do you actually have to amend the description?

Only when an inconsistency has legal significance - meaning it actually causes the patent or application to fall foul of a specific EPC requirement. The requirements that could be in play include Articles 52–57 (patentability), Article 76(1) (divisionals), Article 83 (sufficiency), Article 84 (clarity and support), and Article 123(2)/(3) (amendments). If an inconsistency doesn't cause a problem under any of these, then it seems that no adaption of the description is necessary.

The answers in a nutshell

What this means in practice

This decision confirms that patent applicants and proprietors are not required to carry out a wholesale "clean-up" of the description to remove all unclaimed subject-matter whenever claims are narrowed. However, where an inconsistency genuinely compromises compliance with a substantive EPC requirement - for instance, where unclaimed disclosure in the description casts real doubt on the meaning of an amended claim - adaptation will be necessary. As an obiter remark, the Enlarged Board noted that adapting the description during pending appeal proceedings is generally the most efficient course and is preferable to remitting the case to the first instance.