The expert often plays a crucial role in patent litigation in both Germany and the United States. Determination of facts and application of law to facts frequently require a technical understanding that only an expert can provide. Despite the similarity of the problem of conveying information to the decision-maker, the role of the expert in the two systems and the manner in which the problem of providing technical knowledge necessary for the decision is solved are so very different, that German jurists who transfer their German experiences and expectations over to US procedures, are in danger of experiencing great disappointment if not disaster. American practices relating to the selection and preparation of expert witnesses are so different from European practices, that their explanation to European jurists is said to cause "amazement... bordering on disbelief. " Knowledge of American practices can both ease involvement in an American patent lawsuit, whether as party or as expert, and contribute to a better understanding of the risks and costs of patent lawsuits in the United States.
The Expert in U.S. and German Patent Litigation, CI IIC: International Review of Industrial Property and Copyright Law 595 (1991)