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

VO, which has offices in the Netherlands, Belgium and Germany, is the second European IP firm to secure external backing this week
The Bardehle Pagenberg attorneys-at-law discuss the firm’s Managing IP EMEA Awards 2026 success, Unified Patent Court litigation strategy, and evolving European patent trends
A patent battle between two legal tech companies and a loss for Elon Musk’s xAI against OpenAI were also among the top talking points
With drug prices a hot topic in the US, courts are seemingly more reluctant to prevent the entry of generics to the market
Academic Eden Sarid joins us during Pride Month to discuss queer expression and IP law, Patagonia v Pattie Gonia, and how queer and AI-generated creations both pose novelty concerns
Patent attorney Michael Henson joins the firm to lead its freshly launched blockchain and digital assets practice
A dispute over mammogram technology, and a development in the case between GSK and Moderna were also among the top talking points in recent weeks
With rankings for Western Europe set to be published on June 25, we sat down with our research lead to find out what practitioners and law firms can expect
Peter O’Sullivan, a professional services executive, says he is looking forward to helping Pearce IP become the leading life sciences firm in Australia and New Zealand
Matteo Di Lernia, advocate at LCA Studio Legale, unpicks the CJEU’s ruling in M.M. Ristorazione v Villa Ramazzini, including its impact on litigation strategies
Gift this article