Although mental health workers have long played an active and influential role in the provision of services to youth court, they have, as yet, devoted little effort to establishing standards to guide their procedures. The experiences of clinicians at the Metropolitan Toronto Forensic Service (METFORS) help in identifying some of the difficulties associated with current practices. The lack of specific standards which define the conduct of assessments has posed a number of problems which have brought mental health professionals into disrepute. In general, criticism has focused on the irrelevance of evidence to legal questions, the worth of legal and moral opinions proposed, the employment of data which are unreliable and invalid, and the use of jargon which is incomprehensible to legal decision makers. Before a proper assessment can be conducted the clinician must have a keen understanding of the reasons why the youth was referred for assessment. Opinions formulated from assessments and conveyed in reports should reflect a high degree of reliability and validity. Mental health professionals working in the juvenile justice system should be well informed about legal issues. 17 references. (Author abstract modified)