Driver 1921. Although this was not the first time a psychologist was used as a witness, it was the first time the psychologist was used to confirm mental stability during the crime.(Weiner , IB, & Hess, AK ) In this case the psychologist's findings were not used to make a final verdict on the driver. Another important case that occurred in the field of forensic psychology was Frye v. United States of 1923. (Weiner, IB and Hess, AK) In this case it set the standard for the acceptance of the forensic psychologist in the courtroom court. This case represented a huge breakthrough in the field of psychology. The first case in which the defendant was found guilty by reason of insanity was People vs. Hawthorne in 1940. In this case a man killed his wife and the courts would not allow a psychologist with a PhD to be the expert witness. This path went to the Supreme Court which upheld a rule stating that a person should not rely on whether or not he or she has a Ph.D. One of the last court cases that helped the expansion of the field of forensic psychology was Jenkins Vs United States 1962. In Washington courts they ruled that psychologist can be an expert witness when dealing with mental illness. After this ruling, many courts in the United States began to allow psychologists to become expert witnesses. In these court cases