Plausibility: A conditio sine qua non of Patent Law?

(2020) Intellectual Property Law Quarterly 180-203

58 Pages Posted: 21 Aug 2021

Date Written: June 1, 2020


The plausibility test requires that all valid patents make a technical contribution which is at least plausible. Plausibility originates in the case law of the EPO but has been most enthusiastically embraced by the UK courts such that it finds application across virtually all grounds of revocation. Although lacking a legislative basis, plausibility is rationalised on the grounds that “the patent monopoly should correspond to and be justified by the technical contribution to the art”. Nevertheless, plausibility suffers from many practical, legal and conceptual difficulties—clarity on the nature of the evidential burden; its compatibility and place within the legal framework; and how broader policy concerns should influence its application, are all factors that have yet to be adequately addressed. However, plausibility’s objectives are fundamentally linked to patent law’s conception of the ‘invention’ and arguably should be formulated as such. Adopting this approach would bring greater coherency to the law, and recognise plausibility as a true conditio sine qua non of the patent system.

Keywords: European Patent Office, Patent applications, Patents, Plausibility, Validity

Suggested Citation

Slade, Alison, Plausibility: A conditio sine qua non of Patent Law? (June 1, 2020). (2020) Intellectual Property Law Quarterly 180-203, Available at SSRN:

Alison Slade (Contact Author)

University of Leicester ( email )

University Road
Leicester LE1 7RH, LE1 7RH
United Kingdom

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