European Patent Office Updates Its Guidelines For Examination

The Guidelines for Examination in the European Patent Office (EPO Guidelines) are publicly accessible instructions on the practice and procedure to be followed in the various aspects of the examination of European patent applications and patents in accordance with the European Patent Convention (EPC) and its Implementing Regulations. The EPO Guidelines are routinely modified to reflect changes in procedure and in the application of law. The April 2026 edition entered into force on 1 April 2026, superseding the April 2025 edition.

1. Updates in Procedural Matters

The updated EPO Guidelines include important changes in certain procedural matters before the European Patent Office (EPO):

• The Programme for Accelerated Prosecution of European Patent Applications (PACE)is a mechanism by which applicants can accelerate the grant procedure before the EPO, with the aim of obtaining key communications for the applicant (such as the communication of intention to grant under Rule 71(3) EPC) within reduced timeframes. Whilst such acceleration could previously be sought for both the search and examination stages of prosecution, acceleration has, with effect from 1^st February 2026, been limited to the examination stage only. Such a change reflects the general efficiency of the EPO in issuing a search report – the mean time to such issue from the date of payment of the search fee being 5.5 months – which renders acceleration at this earlier stage of prosecution of limited value.
• The EPO Guidelines also reflect a simplification of the evidence assessed by the EPO in reaching decisions. The Guidelines formerly presented a number of instances where a party seeking to rely on a disputed fact had to provide enough evidence to demonstrate “on the balance of probabilities” that the fact was true. Such instances have in the main been changed to reflect that the EPO will now follow the principle of free evaluation of evidence

• The EPO Guidelines now reflect the possibility of filing European patent applications with drawings in color. A first caveat to doing so is that drawings in color may not be acceptable at other patent offices, such as the UKIPO (UK) and JPO (Japan). Further patent offices may only accept color drawings if the invention cannot be disclosed without them, such as the USPTO (United States). International applications under the Patent Cooperation Treaty (PCT) should also be considered carefully. Under current practice, international applications should be filed in black and white: where a European application with color drawings is relied upon for priority, the international application will be converted to black and white and technical information previously represented by the color drawings may be lost.

2. Updates in Substantive Matters

2.1 Claim Interpretation

The EPO Guidelines on claim interpretation have been amended to reflect the Enlarged Board of Appeal’s decision in G1/24 (Heated Aerosol) and, as a consequence, applicants are urged to exercise caution as to their use of terms in the description and claims of the patent specification.

In the updated Guidelines for Examination in the European Patent Office at Part F, Chapter IV, Section 4.1 (Clarity), there is retained the statement that “the meaning of the terms of a claim must, as far as possible, be clear for the skilled person from the wording of the claim alone”. However, in Part F, Chapter IV, Section 4.2 (Interpretation), the EPO also expressed that:

“The description and any drawings are always referred to when interpreting the claims, and not just in the case of a lack of clarity or ambiguity (G 1/24).

However, when assessing patentability, the description and drawings cannot be relied on to read into the claim a restrictive feature not suggested by the wording of the claim.

If, on the other hand, the description provides a special broad definition of a term used in a claim, the claim must be interpreted in the light of that broad definition when assessing patentability, provided this interpretation is technically meaningful.

Otherwise, each claim must be read giving the words the meaning and scope which they normally have in the relevant art.

If, in particular cases, the description gives the words a special meaning by explicit definition or otherwise, the division will, so far as possible, require that the claim be amended in such a way that the meaning is clear from the wording of the claim alone. 

In other words, where a narrower interpretation of a claim term exists in the description of the application or patent, this narrower meaning will not be read into the claims automatically. Instead, the applicant or patentee will be required to amend the claims. Conversely, claim terms may be given a broader meaning if this is evident from the description and is technically sensible.

2.2 Novelty

Three major changes in the assessment of novelty have been incorporated into the EPO Guidelines.

2.2.1 Decision of the Enlarged Board of Appeal G1/23

Decision G1/23 Interpretation of G 1/92 (enablement requirement for products put on the market for forming part of the state of the art within the meaning of Articles 54(2) and 56 EPC)) represents an important decision on public prior use and its principles have now been reflected in the EPO Guidelines at Part G, Chapter IV, Sections 2 and 7.2.1. Specifically, G1/23 relaxed the conditions in which an earlier prior-use disclosure would be interpreted as novelty destroying prior art. In particular:

• “[A] product put on the market before the date of filing of a European patent application cannot be excluded from the state of the art....for the sole reason that its composition or internal structure could not be analysed and reproduced by the skilled person before that date”.
• Technical information about such a product which was made available to the public before the filing date forms part of the state of the art within the meaning of Article 54(2) EPC, irrespective of whether the skilled person could analyse and reproduce the product and its composition or internal structure before that date.

In effect the Guidelines now confirm the requirement for an enabling disclosure does not apply to – naturally occurring or synthesized - products put on the market: a product placed on the market, together with its analysable properties, forms part of the state of the art. Reproducibility is not required: the requirement is inherently fulfilled by the skilled artisan's ability to obtain and possess the marketed product.

It is considered that Decision G1/23 effectively introduces an “on-sale bar” into issues of patentability before the EPO and this has been reflected in the EPO Guidelines.

• “[I]f an object is unconditionally sold to a member of the public…the buyer thereby acquires unlimited possession of any knowledge which may be obtained from the object. Even where in such cases the object's specific features cannot be ascertained from an external examination, but only by further analysis, those features are nevertheless to be regarded as having been made available to the public”.

2.2.2 Selection Inventions

The newly issued EPO Guidelines reflect a simplification of the law relating to the novelty of selection inventions, that is those inventions which involve selecting individual elements, subsets or subranges from a more generic disclosure in the prior art.

Historically a three-pronged novelty test was applied in this context. A sub-range selected from a broader numerical range disclosed in a prior art reference could be considered novel where: the selected sub-range was narrow; the sub-range was sufficiently far removed from any specific examples disclosed in the prior art reference; and, the skilled person, in the light of the teaching of the prior art reference, would not seriously contemplate working in the selected sub-range.

With reference to the new EPO Guidelines in Part G, Chapter VI, Section 7, this test has been replaced instead by a reference to the EPO’s preferred gold standard of assessment: “[a] subrange selected from a broader numerical range of the prior art is considered novel if it cannot be established that, on application of the “gold standard”, the skilled person, using common general knowledge, can directly and unambiguously derive the selected subrange from the prior art (G 2/10, T 1688/20).”

2.3 Further Medical Use Claims

Article 54(5) EPC states that the patentability of a substance or composition is not excluded for any specific use in a method referred to in Article 53(c) EPC – a method of treatment of the human or animal body by surgery or therapy, or a diagnostic method practiced on the human or animal body - provided that such use is not comprised in the state of the art. The updated EPO Guidelines include new guidance on novelty assessment under this provision.

2.3.1 EPO Guidelines in Part G, Chapter VI, Section 6.1.2.1:

A document is prejudicial to the novelty of a claim directed to a specific further medical use if it: (i) clearly identifies the essential conceptual features of the therapeutic treatment,i.e. the substance/composition used for treating the medical indication and any essential features of the treatment; and, (ii) plausibly establishes the underlying therapeutic effect. Plausibility may be established by way of data or scientific reasoning but does not impose any requirement that the mechanism underlying the therapeutic effect be explained. 

Hence, if a prior art document discloses the performance of clinical trials - such as Phase I, II or III studies - but fails to disclose any positive results of these trials, then such a document may not be noveltydestroying because requirement (ii) (plausibility) may not be fulfilled. Since clinical trials fail more often than they succeed, the mere announcement of a clinical trial is in itself not enough to make the claimed invention available to the public. 

2.3.2 EPO Guidelines in Part G, Chapter VI, Section 6.1.2.2:

The treatment of a known clinical indication in a different patient group – wherein the difference is based upon inter alia age, gender, weight, a physiological parameter or a biomarker - may represent a new specific use under Art. 54(5) EPC. The patient sub-group can also be defined actively in the medical use claim, conventionally via reference to the step by which such a group is determined. 

2.3.3 EPO Guidelines in Part G, Chapter VI, Section 6.1.2.3:

Where appropriate, medical use claims may include, in the definition of the therapeutic indication, mechanistic features relating to a mode of action underlying the therapy. However, when the mechanism is the only difference between the claimed invention and the prior art, the mechanism should not merely be an explanation of a mechanism that underlays a previous therapeutic use.