There are several avocats who specialize in patent cases, especially in Paris. In order for such evidence to be used in an infringement action, the plaintiff must then commence such an action for infringement within 15 days. If the main action is not commenced within this period, the plaintiff may be liable to the alleged infringer for any damage caused to him by the saisie. Unlike Germany and Japan invalidity of the patent being sued on is a defence to an infringement action and the defendant can counterclaim for revocation of the patent. If this occurs, the patentee must submit the revised claims to the Patent Office for its approval.
Formal hearings are also before a three judge panel.
Evidence is in the form of documents or actual articles, possibly together with reports from a party's experts. It is not normal for the court to hear live testimony and the whole procedure is largely in writing. Normally, there will be a number of hearings prior to the final hearing. One problem that does occur in France is that as a result of the relatively rapid rotation of judges through various judicial posts, there may be fairly frequent changes of judges throughout the procedure. This can lead to some inefficiency and unpredictability.