Recent highly publicised events have understandably worried some expert witnesses, including psychiatrists. This commentary seeks to encourage those who have invaluable expertise to offer the courts to continue to act as expert witnesses. The Civil Procedure Rules and the Criminal Procedure Rules are helpful to some extent in allaying any fears that expert psychiatrists may have. They are, however, matters of form. More important, it is suggested, are the principles that operate and that, at least in part, lie behind the Rules. Those principles are often, in fact, not unfamiliar ones. Moreover, some of the most fundamental legal principles applied in the courts operate to circumscribe the role of expert witnesses, thus protecting them, provided that they do not go beyond the limits of their expertise.