summary background There is a lack of clarity and some concern about the role that the concept of 'free will' plays in the assessment of legal accountability in forensic psychiatry. People are particularly concerned that the 'free will' concept might embroil psychiatrists in difficult philosophical problems. Recently it has been suggested that in order to avoid confusion it would be better if forensic psychiatrists ignored the free will concept completely. aim To analyse the problem of free will in forensic psychiatry and to investigate how psychiatry can deal with it. method Discussions took place about recent forensic psychiatric and philosophical literature of free will and legal accountability, particularly in the Netherlands. results Free will is a serious philosophical problem and no solution is yet in sight. Psychiatrists, however, should not let themselves be distracted by metaphysical problems. The problem of free will points to a significant lack of clarity concerning the nature of the assessment of legal accountability itself. The matter needs to be researched and empirical ethics seems to be a possible way of approaching the problem. conclusion The problem of free will demonstrates the importance of doing (interdisciplinary) research into the assessment of legal accountability, for instance, via empirical ethics.