How can facts be proven in IP litigation?
Evidence presented to a court which assists in its determination of factual issues, is of great importance in IP litigation. Depending on the respective national civil procedure provisions, various categories of evidence may exist, such as real evidence, documentary evidence, and witness evidence. In IP litigation, two particular forms of evidence have been shown to be useful. These forms are expert evidence and consumer surveys.
Many courts rely upon expert evidence in IP litigation, in particular in the area of patent litigation. The technical content in many patent cases can be very complex. In these circumstances, expert evidence is a valuable tool for the judge in determining highly specialized and technical issues of fact.
However, in a number of countries that have specialized judges/bodies, both in patent law and the technological fields, the average case is often decided without the assistance of an expert. For example, Germany's use of a specialized judiciary is said to have resulted in more than 90% of patent infringement cases being settled without any expert evidence, saving time and money for the parties involved.
In particular in the area of trademark litigation, as well as in unfair competition cases, the consumer or market survey has arisen as an important evidentiary tool. If admitted into evidence, the results of such a survey can provide evidence on the state of public opinion in relation to a particular trademark. Consumer surveys also can demonstrate whether a trademark has acquired such reputation that it qualifies as a well-known mark. A third potential area of using survey results may be seen in cases where the question of confusion is relevant; in practice, however, reliance on surveys in this context is rather limited.
Another aspect related to evidence, which is of great practical importance, concerns the issue of burden of proof, or in other words, which party will have to furnish certain elements of evidence. In general, most civil procedures follow the principle that each party has to deliver the evidence, which supports the facts on which the claim is based. However, there are a number of exceptions which may lead to a (partial) shift of the burden of proof. For example, Art. 34 of the TRIPS Agreement establishes a special burden of proof rule for proceedings where the subject matter of a patent is a process for obtaining a product. In the European Union, the European Court of Justice (ECJ) has recently rendered a fundamental judgement relating to the burden of proof in cases of trademark exhaustion (case C-244/00 - stüssy, of April 08, 2003): The ECJ argued that, with a view to the need to protect the free movement of goods, this burden must be shared where there is a risk that placing the burden of proof on the defendant would allow the trade mark owner to partition national markets. A more balanced rule on the burden of proof was therefore defined by the ECJ.