Mancini, Lombroso, Garofalo, Albrecht, Benedikt, Büchner, Moleschott, Despine, Fouillée, Letourneau, Maudsley, Bruce Thompson, Nicholson, Minzloff, Notovich and other European criminal lawyers, physiologists and anthropologists have devoted themselves with peculiar zeal and rare acuteness to the study and solution of obscure and perplexing problems of psycho-pathological jurisprudence, and have drawn nice and often overnice distinctions in determining degrees of personal responsibility. Judicial procedure no longer stops with testimony establishing the bald facts in the case, but admits also the evidence of the expert alienist in order to ascertain to what extent the will of the accused was free or functionally normal in its operation. Here it is not a question of raving madness or of drivelling idiocy, perceptible to the coarsest understanding and the crassest ignorance; but the slightest morbid disturbance, impairing the full and healthy exercise of the mental faculties, must be examined and estimated. If “privation of mind” and “irresistible force,” says Zupetta, are exculpatory, then “partial vitiation of mind” and “semi-irresistible force” are entitled to the same or at least to proportional consideration. There are states of being which are mutually contradictory and exclusive and cannot co-exist, such as life and death. A partial state of life or death is impossible; such expressions as half-alive and half-dead are hyperbolical figures of speech used for purely rhetorical purposes; taken literally, they are simply absurd. It is not so, however, with states of mind. The intellect, whose soundness is the first condition of accountability, may be perfectly clear, manifesting itself in all its fulness and power, or it may be partially obscured. So, too, the will, whose self-determination is the second condition of accountability, may assert itself with complete freedom and untrammelled force, or it may act under stress and with imperfect volition. Moral coercion, whether arising from external influences, abnormities of the physical organism or defects of the mental constitution, is not less real because it is not easy to detect and may not be wholly irresistible. For this reason, it involves no contradiction in terms and is not absurd to call an action half-conscious, half-voluntary, or half-constrained. “Partial vitiation of mind” is a state distinctly recognized in psychiatrical science. In like manner, there is no essential incongruity in affirming that an impulse may be the result of a “semi-irresistible force.” But these mental conditions and forces do not manifest themselves with equal obviousness and intensity in all cases; sometimes they are scarcely appreciable; again they verge upon “absolute privation of mind” and “wholly irresistible force;” and it is the duty of the judge to adjust the penalty to the gradations of guilt as determined by the greater or less freedom of the agent.