Plausibility

Plausibility concerns the support provided by a patent application for the technical effect relied on. In pharmaceuticals and biotechnology, it requires examining the relationship between claims, the original teaching and experimental data. It is not a standalone requirement applied indiscriminately to every patent.

Two different questions: inventive step and sufficiency

Inventive step: what effect may distinguish the invention from the prior art? Sufficiency: can the skilled person perform the claimed invention using the disclosure and common general knowledge? In a therapeutic-use claim, achieving the claimed effect may engage the second question. The tests are distinct.

The ruling in G 2/21

On 23 March 2023, the EPO Enlarged Board held that evidence supporting an effect for inventive step cannot be disregarded solely because it post-dates filing. The relied-on effect must be derivable by the skilled person, using common general knowledge, as encompassed by the technical teaching and embodied by the same originally disclosed invention.

Neither rejecting every later experiment nor invoking a new result without analysing the original application is sufficient. The order concerns inventive step. Paragraph 77 distinguishes sufficiency: later evidence cannot cure an initial deficiency concerning the claimed therapeutic effect in the circumstances described there.

Read the evidence in context

• Identify the precise claim and disputed effect. Distinguish an allegation from an established result.
• Locate relevant passages in the original application and common general knowledge at the relevant date.
• Compare experimental models, compounds, doses, indications and populations actually studied with the claimed scope.
• Distinguish confirmation of the original teaching from an attempt to supply missing teaching later.

Absence of a clinical trial in the patent does not automatically establish insufficiency. Conversely, a later marketing authorisation alone does not answer what the application taught at filing.

Do not assume uniformity between jurisdictions

G 2/21 provides an EPO framework. Its application to the facts and interaction with national or UPC litigation require assessment. In Warner-Lambert v Generics ([2018] UKSC 56, paragraph 15), the majority found certain pregabalin claims insufficient. That outcome depends on the patent and scientific record, not on a conclusion applicable to every second-medical-use patent.

Prepare the assessment

Gather the original application, claim versions, dated scientific publications and experiments with their protocols. Legal and scientific expertise work together. Drafting and EPO proceedings are coordinated with patent attorneys.

Sources

EPO, G 2/21, order and paragraphs 74 to 77 (French). Warner-Lambert v Generics, [2018] UKSC 56, paragraph 15.

Related concepts

Second medical use · Launch at risk