The author analyses the moral aspects of the work of a court expert witness in the perspective of general professional ethics, ethics of the legal professions, informal professional standards of the profession, quality norms applying to forensic expertises, and finally ethical problems arising out of the domestic and international harmonisation in forensic sciences. The author concludes that the morality of the expert is compounded of the basic principles of the ethics of the legal professions (loyalty, discretion, responsibility, reliability, high quality of services) and the principles of ethics specific to the non-legal specialist in a given area. This generates analogies to business ethics.