The data obtained in a clinical trial are facts and cannot formally be owned by anybody. However, knowledge that results from these facts can be proprietary and represents considerable commercial value. Clinical research with medicines or devices is often a collaboration between scientists and commercial companies, and this may generate a dilemma. The company may want to keep the knowledge hidden, for instance to obtain patents, whilst the scientist requires rapid publication. In the Netherlands this is resolved as much as possible by a contractual agreement. This codifies the formal position between a company and a medical center. However, the theory does not always agree with the practical situation in which many loopholes exist. These are discussed in the paper, based upon a hypothetical case.