ment is no defense. His act is to be judged by the standard of conduct of an ordinarily prudent man under the circumstances. In conduct resting upon judgment, opinion, or theory, however, a different rule has been recognized. This distinction has been well pointed out in the case of The Tom Lysle (D. C.), 48 Fed. 690, where it is said:
“ ‘The distinction between an error o£ judgment and negligence is not easily determined. It would seem, however, that if one, assuming a responsibility as an expert, possesses a knowledge of the facts and circumstances connected with the duty he is about to perform, and, bringing to bear all his professional experience and skill, weighs those facts and circumstances, and decides upon a course of action which he faithfully attempts to carry out, then want of success, if due to such course of action, would be due to error of judgment, and not to negligence. But if he omits to inform himself as to the facts and circumstances, or does not possess the knowledge, experience, or skill which he professes, then a failure, if caused thereby, would be negligence.’ *
“It would be unreasonable to hold a properly qualified physician or surgeon responsible for an honest error of judgment, where* as in the instant case, he is called upon to act in an emergency and must choose between two courses of action either one of which involves the possibility of gravest hazard to the patient.”
In Delahunt v. Finton, 244 Mich. 226, it was said:
“It is settled that a surgeon may lawfully perform, and it is his duty to perform, such operation as good surgery demands, in cases of emergency, without the consent of the patient. * In so doing he is not liable for an honest error of judgment. ’ ’
The testimony showed that defendant claimed that he encountered an emergency when he found the diseased condition, scar tissue, etc., and he had to exercise his judgment in determining how deep