EPO: Proving plausibility before the EPO

Managing IP is part of Legal Benchmarking Limited, 1-2 Paris Gardens, London, SE1 8ND

Copyright © Legal Benchmarking Limited and its affiliated companies 2026

Accessibility | Terms of Use | Privacy Policy | Modern Slavery Statement

EPO: Proving plausibility before the EPO

A common dilemma for inventors and applicants before the European Patent Office is whether an invention is sufficiently mature for a patent application to be filed. Although a proof-of-concept is often established at the date of filing, an inventor does not always have the opportunity to investigate every aspect of their invention before a patent is filed.

Typically, the EPO has been more relaxed than the USPTO or SIPO regarding this issue, and if an applicant at the EPO encounters an objection that a particular aspect of a claimed invention is not sufficiently disclosed, such an objection can typically be overcome by providing experimental evidence to the EPO that the aspect in question actually works as proposed. Experimental evidence of this nature can be post-published, i.e. the patent application can be supported by experiments carried out after the filing date.

EPO case law requires in principle that a patent claim should be examined for compliance with the requirements of sufficient disclosure (Article 83 EPC) on the basis of the application documents as originally filed. In practice, however, this requirement has not been strictly applied, and patents and patent applications often survive objections of lack of sufficiency, especially if post-published data can be provided.

Some recent decisions of the EPO Boards of Appeal in the pharmaceutical field have developed the existing case law around how plausible the technical effect of an invention must be at the filing date of the patent application.

In decisions T 0488/16 (Dasatinib I) and T 0950/13 (Dasatinib II), the Board required that the technical problem underlying the invention was at least plausibly solved at the filing date. This required technical evidence if the effect is "neither self-evident nor predictable or based on a conclusive theoretical concept". Post-filed evidence and declarations by experts that the products did in fact work as envisaged were not sufficient, and the patents were deemed to lack inventive step.

Decision T 2500/12 (Alzheimer) concerned an immunogen for a pharmaceutical composition in the accepted second-medical use form (for use in the treatment, prevention or amelioration in an animal of Alzheimer's disease or other diseases characterised by amyloid deposits). The Board was not convinced that the suitability of the immunogen claimed for the particular treatment was shown in the application as filed, or in the prior art. The patent claim was found to be insufficiently disclosed.

If these decisions form part of a trend, obtaining valid patent claims on the more speculative aspects of an invention may prove to be more difficult before the EPO.

Edward J Farrington

Inspicos A/S

Kogle Allé 2

DK-2970 Hoersholm

Copenhagen, Denmark

Tel: +45 7070 2422

Fax: +45 7070 2423

info@inspicos.com

www.inspicos.com

more from across site and SHARED ros bottom lb

More from across our site

News of White & Case asking its London staff to work from the office four days a week and a loss for Canva at the Delhi High Court were also among the top talking points
With boutiques offering an attractive alternative to larger firms, former Gilbert’s partner Nisha Anand says her new firm will be built on tech-smart practitioners, flexible fees, and specialised expertise
IP specialists Jonathan Moss and Jessie Bowhill, who worked on cases concerning bitcoin, Ed Sheeran, and the Getty v Stability AI dispute, received the KC nod
Hannah Brown, an active AIPPI member, argues that DEI commitments must be backed up with actions, not just words
A ruling in the Kodak v Fujifilm dispute and a win for Google were among the major recent developments
Nick Aries and Elizabeth Louca at Bird & Bird unpick the legal questions raised by a very public social media spat concerning the ‘Brooklyn Beckham’ trademark
Michael Conway, who joined Birketts after nearly two decades at an IP boutique, says he was intrigued by the challenge of joining a general practice firm
The private-equity-backed firm said hires from DLA Piper and Eversheds Sutherland will help it become the IP partner of choice for innovative businesses
The acquisition is expected to help Clorox bolster its position in the health and hygiene consumer products market
AIPPI, which has faced boycott threats over the 2027 World Congress, says it has a long-standing commitment to engagement and geographic rotation
Gift this article