Increasing specialisation and the growth of automated advice-delivery systems are creating new problems in legal responsibility and ethical behaviour. Engineering, planning, legal, and medical workers can expect early encounters with these difficulties, which are essentially concerned with a new interpretation of 'due care' and of 'professional liability'. The precipitating factor in this debate is the emergence of usable 'expert' systems, which emhody judgmental and operational knowledge, and are often designed to mimic the behaviour (if not the public pronouncements) of acknowledged experts in the field. The task of the knowledge engineer and of the professional worker using -- or expecting others to use -- such automated advisory systems raises ethical problems both for individuals and for professional and learned societies. Some of these are considered in this paper with special reference to the arms-length delivery of engineering, planning, and regulatory advice.