Jay H. Ziskin, 77, psychologist and lawyer who was a nationally known expert on psychological testimony. After serving in the Army Air Corps during World War II, Ziskin earned a law degree and a doctorate in psychology from USC. He later became chief research psychologist for the USC Institute of Psychiatry and Law and served as dean of the counseling center at Cal State L.A. Ziskin wrote a popular three-volume guide, "Coping With Psychiatric and Psychological Testimony" and "Brain Damage Claims: Coping With Neuropsychological Evidence." Although he was frequently called upon as an expert witness in criminal trials, Ziskin long advocated banning expert psychiatric testimony. "There is absolutely no scientific or medical criteria for determining the presence or absence of mental capacities," he said in 1981. Lay witnesses such as neighbors or family members, he said, were often as competent as psychologists to offer opinions on a defendant's mental capability. On June 14 in West Los Angeles of prostate cancer.