It is necessary for a clinical psychologist to determine adequately whether a person is structurally normal or abnormal. Such a diagnosis prejudges work with the person either in the penal system or in the health care one. Several hundred professional tests are successfully used in professional psychology and clinical medicine. It should be noted that most of them have been developed in clinical medicine and foreign psychiatric clinics. The article analyzes in detail the projective tests as a clinical method of psychodiagnostics. Rorschach test, Shondi test, M. Luscher color test, TAT method, and others are the most popular among the specialists. Their distinctive feature from questionnaires is that the obtained result processing is not quantitative, but qualitative. Patient diagnosis depends on the experience and value orientations of a clinical psychologist and psychiatrist. Scientific schools and the culture of various countries play a significant role in this. Although there are certain international criteria for the diagnosis of personality. They are based on DSM–IV diagnostic table. Its indicators are more intended for a psychiatrist and psychotherapist. The authors raise a very unequivocal problem of using personal questionnaires from a legal point of view. Foreign studies reveal the impact of clinicians on the criminal law system, as well as the impact of legislation on the psychiatric clinics system. In the late XX century, a complex forensic psychological and psychiatric examination (CSTI) appeared at the junction of the expert application of psychiatry and psychology. It is important to note that the objects of its research are persons with borderline neuropsychiatric disorders and character anomalies. A key aspect in the activities of professional psychologists and psychiatrists is studying the validity in diagnosis using a case of the «Picture of a Man»(RFC) test. The results of foreign studies have shown that the decisions that clinical psychologists make about their patients are nothing more than a projection of their preconceived opinions. Thus, when making a fateful decision for each individual person, in no case should one make mistakes.