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

Cookies Settings

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

The explosion of data centres has prompted patent pool operators to create new licensing opportunities
The court struck out copyright claims brought by Ladbrokes owner Entain, saying that ownership details should have been completed before litigation began
Düsseldorf has overtaken Munich as the UPC's busiest division, while firms including Winston Taylor, Clifford Chance, and Hoyng Rokh Monegier featured in disputes involving Abbott, Essity, Amazon and Hurom
The managing partner gave up an equity partnership track in New York to build a practice in India. More than a decade later, she discusses entrepreneurship, leadership, and why women should not wait before taking the next step
Vice presidents Shinya Jitsuhiro and Hirohisa Suzuki discuss litigation trends in Japan, recruitment challenges and clients’ international expansion
IP boutique Petillion represented IKEA in the dispute, which concerned the use of the multinational’s trademarks in an immigration-focused campaign. The firm tells Managing IP how it secured the outcome
The Pizzeys-Griffith Hack integration was designed to create a stronger Australian IP platform but with several ex-Pizzeys principals now gone, the deal's success may depend on where clients place their trust
Thomas Lonsdale and Hsu Min Chung of HGF explore the practical impact of the EPO’s Enlarged Board of Appeal’s decision in G1/25 and its interplay with G1/24
The firm’s recent IP hire and launch of a new robotics industry group signal an effort to capture work emerging from AI entering the physical world
Another firm sets up shop in Dallas, bringing its patent disputes capabilities to one of the US’s busiest litigation venues
Gift this article