Persons using the insanity defense have a strong motivation to appear insane on the psychiatric pretrial examination to escape criminal prosecution. Psychopathology can then be masked by their posttrial defensiveness. This study attempts to design more effective measures for analyzing defensiveness on objective personality tests in common use in forensic psychology. The Minnesota Multiphasic Personality Inventory (MMPI) and 16 PF were administered to 45 forensic patients, and scores on 5 derived measures of defensiveness were computed. The 10 highest and 10 lowest scoring subjects were assigned to either a high or low defensiveness group and their responses were analyzed with regard to the schizophrenia, paranoia, psychopathic deviate, and hostility clinical scales and subscales of the MMPI according to past or present items. Results confirm that high defensiveness subjects are selectively and cautiously interpreting items so as to admit to significantly less overall pathology and relatively less pathology than low defensiveness subjects. This finding represents a consistent strategy of defensiveness rather than an artifact of false response bias. Tables, 1 note, and 10 references are included. (Author abstract modified)