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

Cassie Hill, partner at Mishcon de Reya, discusses rebuilding client relationships after maternity leave and the pressures facing women at a pivotal stage of their career
Matthew Asbell discusses why empathy is important in law, being inspired by diverse workplaces and working on the latest, greatest large language model
The new partners add patent trial depth in high-value technology sectors including semiconductors, software, and cloud computing
From seller vetting and proprietary screening technology to brand collaboration and industry partnerships, Temu explains how its intellectual property enforcement programme combats infringement on its marketplace
A handful of US firms have quietly invested in European patent talent. Recent moves by Baker Botts and K&L Gates suggest that trend may be accelerating
Loke Khoon Tan and Stephanie Yip at Dentons explain what brand owners need to know ahead of January 1 2027, when updates to China’s Trade Mark Law come into force
New US bills signal that firms should work with clients to ensure they are complying with potential regulatory requirements
Octavio Espejo of Becerril, Coca & Becerril explains how sweeping patent reforms reshape filing strategies, prosecution, and divisional application practice
The UK Supreme Court’s decision in Tesla v Avanci enhances the UK's attractiveness for global FRAND battles, say lawyers at Simmons & Simmons
PE-backed practices now comprise the majority of ranked firms for patent prosecution in the Netherlands, but competitors are confident about their decision to remain independent
Gift this article