I will here venture the belief that the medical man whose testimony will carry with it the greatest weight, will be he, who, in addition to his own experience, can supplement it by the accumulated experience of many others, whatever be _his_ age or however limited _his_ experience. An eminent lawyer once remarked in my presence: "You doctors make bad witnesses. When asked by counsel, questions which no man can answer, why don't you confess your inability to do so?" I have often seen a medical witness floundering through an attempted definition of insanity--of mind and its relations to matter. Herbert Spencer begins his chapter on mind by declaring that we do not know, and probably never shall know, anything concerning mind. It is in nowise derogatory, therefore, to our intelligence, to admit the same unwelcome truth. To recapitulate, then, the causes, as I understand them, of the merited discredit attending expert testimony in medico-judicial inquiries, are: _First_--A diploma and active practice constituting the only legal requirement for that position. _Second_--Inequality of professional acquirements; an inequality, I may remark, resulting from a difference of industrious habits in the later years of professional life. _Third_--Inharmony among professional men. These, I am persuaded, are the proximate causes of the ridicule and contempt with which medical testimony is at present received in California courts. The remedies for the evil may be briefly stated to consist in: _First_--A united profession, determined to elevate the standard of medical education. _Second_--The formation of local medical societies for the interchange of ideas and harmonious intercourse, and the promotion of mutual improvement in medical and collateral science. _Third_--The establishment in the medical department of the University of California of a Chair of State Medicine for the benefit of those who desire to fit themselves for service in medico-legal investigations.