The European Patent Convention (EPC) contains no explicit requirement for a patent application to contain experimental data in support of the invention. It has therefore been possible to file speculative applications for inventions that are described theoretically, but not experimentally. This strategy permits applicants to obtain an early filing date, which is particularly advantageous in a competitive field of technology.

However, according to the EPC, the claims of an application for a patent must “...define the matter for which protection is sought. They must be clear and concise and supported by the description.” Furthermore, “The description shall ... describe in detail at least one way of carrying out the invention claimed using examples where appropriate.” The EPC therefore infers a requirement for experimental support in an application. But how much 'experimental support' is adequate support? The case law of the Boards of Appeal, which is used to interpret the statutory provisions of the EPC, has provided guidance on this matter.

In the biotechnology field, early cases indicated that description of 'one way' of performing an invention was enough to support a claim of broad scope. For example, in the Genentech/bacterial-expression decision, broad claims were granted that protected a recombinant plasmid for transformation of a bacterial host comprising a regulatory element and DNA. Such claims were granted despite the presence of only one example in the application, which related to a specific bacterial species. In this case it was considered that the invention was generally applicable and that “there is nothing ... that precludes a claim covering entities which may come into being in the future.”

Proof of the invention

Recent case law indicates that there is a requirement for experimental support in an application in cases in which 'proof' of the invention is required. The reasoning behind the decision in a case involving Mycogen (see Box) sums up the current thinking regarding the requirement for experimental support in an application.

If an invention embodies an idea or concept, which is not rendered obvious by prior art publications, then claims of a broad scope can be obtained with little or no experimental support. However, when the broad concept or idea is already in the public domain, the invention itself resting in the actual reduction to practice of the known or obvious idea, then the granted claims will be limited in scope to the breadth of experimental support in the application. In other words, if the invention is based on the achievement of a result, then the achievement of that result must be demonstrated over the whole scope of the claims.

Practically, this means that patent agents and inventors must carefully balance the need for an early patent filing date with the increasingly stringent requirement for experimental data in an application.

What is experimental support?

Just to muddy the waters a little more, it should be noted that 'experimental support' in an application does not necessarily mean 'methods and results of experiments that have been performed'. It can sometimes mean 'methods and the predicted results of experiments we might (or might not!) perform in the future' and which support the application on file. In essence, the experimental support in a patent application might be to a certain degree theoretical — the reasoning for this being that patents can be granted for inventions and a 'theoretical' experiment is an exemplification of the invention. This approach of using 'theoretical' examples must be used with caution, however, as the presence of 'unworkable embodiments' or irreproducible experiments in an application could cause sufficiency problems (described below), which might result in rejection of the patent application.

Finally, it is generally the case that further experiments can be presented, and theoretical experiments substantiated, during the prosecution of a patent application, and this must be taken into account in deciding when to file an initial application.

Support and Sufficiency

The need for support is linked with the requirement that a European patent application be sufficient — that is, according to the EPC it must “describe the invention in a manner clear and complete enough for it to be reproduced by one skilled in the art”, without undue experimental burden. Recent case law has indicated that a patent application can be deemed insufficient if it contains aspects of an invention that do not work or are not reproducible. The danger of 'fabricating' aspects of an invention and 'experimental support' is, therefore, clear.

Experimental support and claim breadth

Are broad claims without substantial experimental support a thing of the past? It would seem not. Cases indicate that broad claims can be obtained with little or no experimental support. However, it seems that in general patent offices are becoming more stringent in their experimental support requirement and therefore the take-home message has to be 'the more the better'.