One approach to the analysis of ethical dilemmas in medical practice uses the "four principles plus scope" approach. These principles are: respect for autonomy, beneficence, non-maleficence and justice, along with concern for their scope of application. However, conflicts between the different principles are commonplace in psychiatric practice, especially in forensic psychiatry, where duties to patients often conflict with duties to third parties such as the public. This article seeks to highlight some of the specific ethical dilemmas encountered in forensic psychiatry: the excessive use of segregation for the protection of others, the ethics of using mechanical restraint when clinically beneficial and the use of physical treatment without consent. We argue that justice, as a principle, should be paramount in forensic psychiatry, and that there is a need for a more specific code of ethics to cover specialised areas of medicine like forensic psychiatry. This code should specify that in cases of conflict between different principles, justice should gain precedence over the other principles.