The ideal psychiatric expert witness is generally conceived of as objective, unbiased and uninvolved in the outcome of the trial in which he is testifying. Nevertheless, the expert witness must inevitably act as advocate, either willingly or unwillingly, either with or without awareness. To accept the advocate role and to pursue it intentionally from the witness stand is honest and ethical if done without deceit. Such advocacy may result in important legal reforms, in benefits to the participants in the trial process and in improvements in the relations between psychiatry and the law.