Article 84 EPC: Claims

Text of Article 84 EPC

In plain English

Article 84 makes three demands. The claims must define the matter for protection, be clear and concise, and be supported by the description. It is the most common objection in EPO examination.

Clarity means the skilled person can tell what falls inside the claim. Relative terms (“thin”, “high temperature”), unusual parameters without a measuring method, optional wording (“preferably”, “for example”) in an independent claim, and result-to-be-achieved features all draw objections. An independent claim must also include the features essential to the invention (Guidelines F-IV, 4.3(ii)).

Support means the claim must not reach beyond what the description justifies, and the description must not contradict the claims. The Guidelines treat embodiments that are no longer covered by amended claims as an inconsistency to be removed or marked as not according to the invention before grant (F-IV, 4.3). A blanket statement at the start of the description does not cure it.

That practice was contested. T 1989/18 (2021) and T 56/21 (2024) found no legal basis in Article 84 or Rules 42, 43 and 48 for requiring the description to be adapted, while other boards required it. T 697/22 referred the issue, and G 1/25 (3 September 2026) answered: where amended claims create an inconsistency with the description and, because of it, Articles 52 to 57, 76(1), 83, 84, 123(2) or 123(3) are not met, the description must be adapted to remove it. The April 2026 Guidelines were written before G 1/25.

After grant, clarity is not a ground of opposition. G 3/14 held that amended claims in opposition can be examined for clarity only where, and only so far as, the amendment itself introduces the lack of clarity.

Key decisions

• G 1/25 : If amended claims create an inconsistency with the description such that Articles 52 to 57, 76(1), 83, 84, 123(2) or 123(3) are not complied with, the description must be adapted to remove it.
• T 56/21 (Adaptation of the description/HOFFMANN-LA ROCHE) : Held that neither Article 84 nor Rules 42, 43 and 48 required the description to be adapted to allowable narrower claims; the question then went to the Enlarged Board.
• G 3/14 : In opposition, amended claims may be examined for clarity only when and to the extent that the amendment introduces non-compliance with Article 84.
• T 409/91 (Fuel oils) : Support and sufficiency both require the monopoly to be justified by the technical contribution, so the extent of disclosure is highly relevant to support.

Common objections

Unclear term

Replace a relative term with a value or range from the description, or show that it has a recognised meaning in the field. Do not add new values that were not disclosed (Article 123(2)).

Missing essential feature

The examiner says the description presents a feature as necessary but the claim omits it. Either add it, or show with evidence that it is not essential and amend the description instead.

Description inconsistent with amended claims

Delete the embodiments that no longer fall within the claims or mark each one specifically, for example “not according to the claimed invention”. Since G 1/25 the obligation is tied to the provisions listed in its order.

Drafting and prosecution tips

• Avoid optional words in independent claims and keep one consistent term for each feature across claims and description.
• Give measurement methods for parameters, and numerical ranges with intermediate fallbacks.
• Avoid “spirit of the invention” and claim-like clauses at the end of the description; the Guidelines ask for them to be removed (F-IV, 4.4).
• When you amend claims at the EPO, file an adapted description at the same time to save a round of correspondence.