A key test for assessing whether an invention has been sufficiently disclosed in Europe is one of plausibility: has the invention plausibly been disclosed in the application as filed? This concept is relevant for both sufficiency (does the patent disclose the information in a manner sufficient to enable a skilled reader to reproduce the invention), and inventive step (has a technical effect been shown, and has it been shown that the claimed invention actually solves a particular problem?).

Sufficiency and inventive step are closely linked in this regard. Broadly speaking, if a technical effect is recited in a claim, e.g. ‘known compound A for use in treating disease Y’, then plausibility of ‘treating disease Y’ is assessed under sufficiency. If the technical effect is not recited in the claims (e.g. new compound A per se), then the plausibility of technical effects is assessed under inventive step. This distinction can be important because inventive step can sometimes be strengthened by later-filed data (see below) while sufficiency must be found solely in the application as filed.

Using a medical use claim again as an example, the patent must provide information rendering it technically plausible that the products have the claimed therapeutic use (as well as information rendering it plausible that the products themselves can be made) (T1599/06, T609/02). The claimed therapeutic effect may alternatively be derivable from the common general knowledge, as well as other prior art (T1437/07, T950/13, T578/06). However, this can obviously lead to inventive step issues, since the common general knowledge can render the claimed therapeutic effect obvious.

The suitability of a product for a claimed therapeutic application can be proven by any kind of evidence, as long as it demonstrates the therapeutic effect (T814/12). A mere statement that a product is useful for a particular indication is not sufficient. Scientific discussion can technically be used as an alternative but, in practice, it is typically required for there to be at least one in vitro example. The case law is clear that in vivo data, or clinical trial results, are not essential.



How much data is needed to justify a claim scope? The EPO guidelines (F-III 1) are clear that, in some instances, even a broad scope can be supported by a limited number of examples, or even one example. It is often beneficial to include technical discussion in the application as to why the scope is justified, for example by identifying features of a claimed product which interact with a particular biological target. This might involve an explanation as to why a particular feature in the core structure of a Markush formula results in better activity, thus justifying generalisation at other positions. The guidelines (F-IV 6.2) indicate that an invention which opens up a whole new field is entitled to more generality in the claims than one which is concerned with advances in a known technology.


Can additional data be supplied at a later stage? G2/21

Any deficiency in plausibility from a sufficiency standpoint cannot be remedied at a later stage with later-filed evidence. If the evidence in the application as filed does not render it at least plausible that the invention can be implemented, the application will not overcome the hurdle of sufficiency, and the case will not proceed to grant. Post-filed data can only be taken into account to back-up the originally disclosed findings (T609/02, T950/13).

From an inventive step perspective, similar considerations apply. T0116/18, referring to T1329/04, states: ‘it is important that the application allows to conclude that the invention had been made, i.e. that problem had been solved, not merely put forward at the filing date of the application’. Issues can arise here as the ‘problem’ in Europe is formulated over a closest prior art document, which may not be known at the time of filing.

As EP practitioners in the field are aware, the issue of whether follow-up data can be filed to support inventive step is currently under review in Europe, as referral G2/21 to the Enlarged Board of Appeal. Pending the outcome of the G2/21 decision, proceedings before the EPO can be stayed when the issue of inventive step turns on post-filed data.

Three different strands of ‘plausibility’ case law have been identified by the referring board in T0116/18 (which we will not discuss here), which show that EP case law is not homogenised in the area. Whilst the referral questions focus on the submission of post-filed data for inventive step assessment, G2/21 may have implications for sufficiency also, since the plausibility case law discussed in the BoA decision under referral (T0116/18) is relevant to both sufficiency and inventive step.

A balance needs to be struck. To forbid post-filed data outright would be unfair on applicants/proprietors when a technical effect needs to be shown over a new prior art document (which the applicant may not have been aware of at the time of filing). This would be particularly relevant for opposition proceedings. On the other hand, to allow post-filed data irrespective of the level of disclosure in the application as filed would result in granted patents for ‘armchair’ or speculative inventions.

We eagerly await the G2/21 decision, as do many others in the life sciences and chemical sectors. We anticipate that post-filed data will continue to be allowable under certain circumstances although its use to rectify fundamental insufficiency or lack of inventive step in an application as filed is unlikely to be acceptable.



In summary, the invention must be ‘plausibly’ disclosed in the application as filed. In practice, for sufficiency and inventive step, it is best to include at least one experimental example, and, if appropriate, some discussion identifying a core feature which justifies a broader claim scope.