How To Use Experimental Evidence In English Patent Litigation

Experimental evidence can play a valuable role in patent litigation. It is not uncommon in patent validity proceedings for an expert will say to they would, when presented with a piece of prior art, have conducted a particular experiment in order to progress the research. Without then conducting the actual experiment that they said they would have done, it is impossible to know what the result of that experiment would have been. Knowing the result of that experiment is sometimes critical to a case, such as when the defendant argues the patent is invalid due to lack of novelty or inventive step or indeed sufficiency.

Experimental evidence is also frequently needed to ascertain the fact of whether or not an allegedly infringing product falls within the claims of a patent. For example, are the particle sizes of the allegedly infringing product within the range specified in the patent? Is there any of the infringing product in the mixture being marketed? Unless the opposing party is prepared to admit the fact in question, the party asserting the fact will need to prove it by experiment.

Experimental evidence is permitted in a number of jurisdictions in Europe, including in oppositions at the European Patent Office (EPO). However, the most rigorous testing of experimental evidence, and therefore the most reliable evidence, is in the High Court of England and Wales.

Any party may submit a report of an experiment at the EPO or in a civil law trial, but the content of that report cannot be challenged in cross-examination and there is little opportunity to explore the details of the experiment or how the experimental protocol was decided upon. There is therefore scope for what Lord Justice Jacob, a former Court of Appeal judge, called ''litigation chemistry,'' by which he meant that experimental protocols can be finessed in order to obtain the ''correct'' result. The procedure at the High Court of England and Wales ensures that experimental evidence can be thoroughly tested by the opposing side.

Procedure

A party wishing to rely on an experiment to prove a fact in High Court proceedings must first serve on the other side a Notice of Experiments. This is a formal document, usually served after disclosure or discovery and before expert evidence is exchanged, which sets out the facts which the party seeks to establish and gives full particulars of the experiments proposed to establish them (CPR 63 PD 7.1). The party receiving the Notice must respond...

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