This article is about the meaning of "standards" in medical treatment. We want to work out especially the function of "standard" as an instrument of legal requirements in medical responsibility, the forming of "standard" with real or normative criterias as well as the guidelines to the right use of standard by the judgement of medical care: 1. The "standard of necessary medical care" is a need but not a totally binding instrument to determine the required medical treatment. It marks special rules that are generally accepted by knowledge of science and practise. 2. "Standard" does not determine a special method for now and forever. It is variable and leaves space for other new methods whose expected success is not unproportional to the risks. The danger of standardization can be the establishing of backwards directed previous methods. 3. A fundamental instrument of establishing "standard" as a judicial criteria are the medical experts. They have the difficult role of mediator between medical methods and judicial responsibility according to the standard of necessary medical care.