During the last 20 years, the application of opinion polls has become an essential component of legal practice in matters concerning the protection of industrial property. In other legal sectors, for instance civil or penal law, the application of opinion polls is almost unknown. The selection of the consumer groups concerned and, especially the construction of correctly formulated questions, are decisive in the practical work of courts as well as for lawyers and producers intending to apply opinion polls for their legal decisions. Problems differ according to the particular aspect which is to be covered by opinion polls. In German rules of civil procedure the evidence given by an opinion research institute is considered expert evidence. Although legal theory has not succeeded in classifying the results of an opinion survey according to the rules of expert evidence, jurisdiction, being well aware of the fact that opinion poll results are of great advantage in fact finding, has disregarded all objections and is nowadays granting to the opinion research specialist the same status as to every other expert.