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The Guidelines for Examination in the European Patent Office (EPO) “the Guidelines” act as an instruction manual with respect to the various aspects of the examination of European patent applications and patents before the EPO, that is they dictate the practice and procedure that should be followed under the European Patent Convention (EPC) and its Implementing Regulations “the Rules”.

The Guidelines are updated on an annual basis and the latest edition, which supersedes the previous version, entered into force on 1 March 2024.

Herein we provide a summary of those changes most likely to affect both clients and practitioners alike.


Historically, the EPO have assessed formal entitlement to priority quite strictly.

In scenarios where a priority application is filed by joint applicants, all of them, or their respective successors in title, must be named on the subsequent priority claiming application for the priority claim to be found valid (the so-called “all applicants approach”).

In the scenario where a priority application is filed by a single applicant but the subsequent priority claiming application is filed in the name of joint applicants, the priority claim is found valid where at least one of the applicants of the subsequent priority claiming application was either the applicant or successor in title to the applicant of the priority application (the so-called “joint applicants approach”).

A variation of the latter approach is the so-called “PCT joint applicants approach” whereby priority is found valid if at least one of the applicants of the PCT application, for whichever designated state, is the applicant or successor in title to the applicant of the priority application.

The burden of proof with respect to claiming priority has traditionally been with the applicant/Patentee.

Following G1-2/22 and the advent of a rebuttable presumption of priority entitlement that ensued therefrom, the Guidelines at Part A-III, 6.1 have been updated to confirm that “absent any substantiated indication to the contrary, there is a strong rebuttable presumption under the EPC that an applicant or joint applicants claiming priority in accordance with Article 88(1) EPC and Rule 52 are also entitled to the claimed priority”.

With respect to the PCT joint applicants approach, and following G 1-2/22, the Guidelines have been updated to confirm that “where an international application under the PCT is filed by joint applicants, including the priority applicant, but without naming the priority applicant as applicant for the European designation, the mere fact of the joint filing implies an agreement between the applicants allowing all of them to rely on the priority right unless substantial facts indicate otherwise”.

The level of evidence required to rebut the presumption of priority entitlement was tested in recently heard and consolidated cases T2360/19, T2689/19 and T2516/19 where Oral Proceedings have been held and the Written Decision is eagerly awaited.

As the representative of a party to those proceedings, and therefore present at the aforementioned Oral Proceedings, it appears that the barrier is extremely high.

Inventive step and the relevance of post published data

G 2/21 was eagerly awaited amongst the patent community but unfortunately the conclusions reached therein, in many respects, were as ambiguous as they were clarifying.

In G 2/21, the Enlarged Board of Appeal of the EPO (EBA) were asked under which circumstances post-published data (i.e. data not present in the application as filed) can be taken into account in the assessment of inventive step. Indeed, it is sometimes the case that during examination or indeed post grant proceedings, applicants/proprietors wish to rely on a technical effect supported by post published data.

Perhaps unsurprisingly, the EBA confirmed that post-published data can be considered in the assessment of inventive step but with the caveat that the skilled person, having the common general knowledge in mind, and based on the application as originally filed, must be able to derive said effect as being encompassed by the technical teaching and embodied by the same originally disclosed invention.

Whilst Part E-IV, 4.1, Part G-VII, 5.2 and Part G-VII, 11 of the Guidelines have been updated to reflect this new test, further guidance as to how to apply this test is lacking and therefore applicants will likely have to wait until case law provides further clarification.

The demise of the 10-day rule

Last year, the long-established EPO “10-day rule”, by which certain documents such as Examination Reports were deemed notified to the recipient (i.e. the applicant or their representative) on the tenth day following the date stamped on the face of the document, was abolished – see our related Article here.

As of 1 November 2023, any Communications issued by the EPO are deemed notified on the day on which they were issued subject to the safeguard that if a document is delivered more than 7 days after the date of the document (and the EPO cannot prove that the document reached the recipient within those 7 days), then any time periods set by the document will be extended by the number of days by which the 7 days were exceeded. Part E-II, 2.3 of the Guidelines has been updated to reflect these changes.

Procedure after grant – Unitary Patent (UP) and Unitary Patent Court (UPC) provisions

On 1 June 2023, the Unitary Patent system came into play. A Unitary Patent (UP) enables a patent applicant to secure patent protection in 17 Member States (a number that will increase as more participating Member States ratify) by filing a single request at the EPO within one month of grant.

Both the General Part and Part C-V, 2.1 of the Guidelines have been updated to reflect the above. Part D-VII, 1.2 and Part E-VIII, 5 have also been updated to reflect that oppositions will be accelerated where either an infringement action or revocation action are pending before the UPC.

Validation States

Part A-III, 12.1 of the Guidelines has been updated to reflect that from 15 January 2024, European patent applicants also have the option of validating in Georgia.

Sequence listings

On 1 July 2022, WIPO Standard ST.26 went live, replacing the former WIPO standard ST.25. Thus, all European patent applications filed after 1 July 2022 and containing DNA, RNA or amino acid sequences must be accompanied by an ST.26 compliant sequence listing.

Whilst on the face of it this seems like a straightforward change, the subject of divisional applications has triggered much debate. If a divisional patent application is filed after 1 July 2022 from a parent application with a filing date before 1 July 2022, the WIPO standard for the parent will be ST.25 but the WIPO standard for the divisional will be ST.26. Thus, the ST.25 sequence listing filed with respect to the parent must be converted to ST.26 before filing with respect to the divisional. Converting an ST.25 sequence listing to an ST.26 sequence listing has the potential to add matter and thus comes with an associated risk.

To mitigate the aforementioned risk, applicants can file the parent application’s ST.25 sequence listing in PDF format as part of the divisional application. Such pages are excluded from the page fee calculation. In such cases, an ST.26 compliant sequence listing must then be subsequently filed. As long as the ST.26 sequence listing is filed before an invitation to file the same is issued, no late furnishing fee will be payable.

Part A-III, 13.2, Part A-IV, 5 and Part A-IV, 5.4 of the Guidelines have been updated to reflect the above.


One sometimes tricky area for applicants pursuing protection for new antibodies is inventive step – structural non-obviousness type arguments are seldom accepted at the EPO for the reason that arriving at a novel antibody by applying techniques known in the art is considered to be obvious. If inventive step is to be acknowledged a surprising technical effect needs to be shown in the application. Part G-II, 6.2 of the revised Guidelines provides examples of surprising technical effects, namely unexpected improvements over prior-art antibodies in one or more properties such as therapeutic activity, stability or immunogenicity. It also confirms that a novel type of functional antibody format may also be considered inventive.

Further revisions have also been made in Part G-II, 6.1.3 of the Guidelines to provide additional guidance on defining antibodies by reference to functional features.

Description amendments

There has been much debate amongst the patent community regarding the legality of the EPO requirement that a description must be amended to bring it into line with the allowed claims, and a referral to the EBA is expected. For now, however, its business as usual and in the revised Guidelines amendments have been made to make clear that inconsistencies between the description and the claims resulting from amendments made to the claims during opposition must be avoided – see Part D-IV, 5

Sufficiency and AI

The field of artificial intelligence (AI) and machine learning (ML) is rapidly evolving and in the latest version of the Guidelines amendments have been made regarding the sufficiency requirements for inventions in this field. Notably, whilst in general, there is no need to disclose a specific training dataset itself, if the technical effect relied upon is dependent on particular characteristics of a training dataset, those characteristics that are required to reproduce the technical effect must be disclosed unless the skilled person can determine them without undue burden using common general knowledge – see Part G-II, 3.3.1.

Designation of Inventor

Part A-III, 5.1 and 5.3 of the Guidelines have been updated to confirm that the inventor must be a natural person and that the EPO will check this.

Registration of transfers of right and licences

Over the last couple of years, several changes have come into effect with respect to the requirements for the registration of transfers of right and licences at the EPO.

With a view to simplifying its procedures and promoting digital transformation, from 1 April 2024 another wave of (hopefully clarifying) changes will be implemented.

Firstly, the EPO will accept a broader range of electronic signatures on documents submitted as evidence to support a request to record a transfer of right or licence.

Specifically, supporting documentation may be authenticated by (i) handwritten signatures, (ii) facsimile signatures (iii) text string signatures and (iv) digital signatures meeting certain criteria.

The practice concerning examination of an individual’s entitlement to sign on behalf of a legal person will also change in that whilst a person who is entitled to sign by virtue of their position within the legal person will still need to expressly state their position, their entitlement to sign will no longer be checked by the EPO.

Lastly, if requests for registration of transfers of right or licences are filed using MyEPO no administrative fee will be due.

Amendments to the Guidelines have been made to reflect the above-mentioned changes – see Part E-XIV, 3.

Our articles are for general information only. They should not be considered specific legal advice, which is available upon request. All information in our articles is considered to be accurate at the date of publishing.


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