A psychiatric evaluation may be based on interviews with the subject, background information, and neurological and psychological tests. Information derived from interviews may consist of explicit verbal responses or nonverbal signs, such that the evaluation relies upon inferences made from such derivatives as speech, nonverbal communication, actions, and behavior. Generally, opinion based on such information is susceptible to controversy and ridicule in the courtroom. To the extent that the opinion of the psychiatrist or psychologist rests upon what the subject has said, it is open to the challenge that the expert is not able to detect deception or malingering. To the extent that the opinion relies upon psychological tests, particularly the Rorschach inkblot and Bender gestalt, the argument may be made that the expert is indulging in an exercise akin to the reading of tea leaves. To the extent that other inferences are possible from the information obtained by the examiner, the testimony is open to the challenge that other conclusions are possible from the same data. Even assuming that the tests have high validity (they evaluate or predict what they are intended to do), they may be challenged on the basis that they were not originally designed to answer the legal question at issue. The vulnerability of psychological testimony to challenge and ridicule in court does not, however, render it useless. The judge or jury must finally decide how to treat the testimony, but without the testimony, there would not be sufficent relevant information important for decisionmaking and the rationalization of the verdict. Fifty footnotes are provided.