to an operation upon her, and such consent is sufficient authority to surgeons to perform the operation. Pratt v. Davis (1906) 224 Ill. 300, 7 L.R.A. (N.S.) 609, 79 N. E. 562, 8 Ann. Cas. 197. The question was squarely presented in State use of Janney v. Housekeeper (1888) 70 Md. 162, 2 L.R.A. 587, 14 Am. St. Rep. 340, 16 Atl. 382, where the husband brought an action for damages against certain physicians for performing an operation upon his wife without his consent. He claimed in this regard that while he consented to an operation to remove a tumor, he expressly dissented to the operation if it was found that the growth was a cancer; the wife, however, was found to have impliedly assented to the operation. Under these circumstances it was held that the husband had no cause of action against the surgeons on the ground of failure to obtain his consent, even though the operation resulted in the death of his wife. The court said: "There is evidence from which a jury might infer that the patient knew that the formation in her breast was a cancer. When the doctors came to the house she had already prepared herself to undergo the operation. If she consented to the operation, the doctors were justified in performing it, if after consultation they deemed it necessary for the preservation and prolongation of the patient's life. Surely the law does not authorize the husband to say to his wife, you shall die of the cancer; you cannot be cured; and a surgical operation affording only temporary relief will result in useless expense. The husband had no power to to withhold from his wife the medical assistance which her case might require. . The consent of the wife, not that of the husband, was necessary. The professional men whom she had called in and consulted, being possessed of skill and scientific knowledge, were the proper persons to determine what ought to be done. They could not, of course, compel her to submit to an operation, but if she voluntarily submitted to its performance, her consent will be presumed, unless she was the victim of a false and fraudulent misrepresentation, which is a material fact to be established by proof. The court below was therefore right in rejecting the first and third prayers of the plaintiffs, which place the burden of proof in regard to consent on the defendants. If the plaintiff alleges that there was no consent, he must establish his affirmation by proof. The party who allows a surgical operation to be performed is presumed to have employed the surgeon for that particular purpose." In M'Clallen v. Adams (Mass.) supra, there was involved the question of the liability of the husband for services in performing an operation upon his wife without his knowledge or consent. In holding the husband liable, where the wife consented, Shaw, Ch. J., speaking for the court, said: "The court are of opinion, upon the facts appearing by the bill of exceptions, that the defendant, by placing his wife under the care of the plaintiff, whom he knew, at a distance from his own residence, for medical and surgical treatment for a danger ous disease, impliedly requested him to do all such acts and adopt such course of treatment and operations as in his judgment would be most likely to effect her ultimate cure and recov ery, with the assent of the wife, and therefore that the operation in question was within the scope of the authority given him. They are also of opinion that the assent of the wife to the operation was to be presumed from the circumstances. Although it might have been an act of prudence in the plaintiff to give the defendant notice of the situation of the wife, and of his intention to perform a dangerous operation, yet we think he might safely trust to the judgment of the wife to give her husband notice from time to time of her situation and intentions, and that it was not necessary, in point of law, for the plaintiff to give such notice, or have any new request, in or der to enable him to recover a reasonable compensation for his services. . . The performance of this operation being within the scope of the plaintiff's authority, if in his judgment necessary or expedient, and that it was so is to be presumed from the fact, it was not necessary for him to prove to the satisfaction of the jury that it was necessary and proper, under the circumstances, or that before he performed it he gave notice to the defendant, or that it would be dangerous to the wife to wait before he performed it till notice could be given to the defendant." In Pratt v. Davis (1906) 224 Ill. 300, 7 L.R.A. (N.S.) 609, 79 N. E. 562, 8 Ann. Cas. 197, supra, the woman operated upon was mentally unsound and hence incapable of giving her consent to an operation upon her to remove both ovaries and the uterus. The case turned upon whether or not the husband consented to the operation, it being apparently assumed that under the circumstances his consent would be sufficient authority for the act of the surgeon in performing the operation, although the case was brought in behalf of the wife. It was, however, found as a matter of fact that the husband did not consent to the operation, and the surgeon was held liable in damages. The court said: "Where the patient desires or consents that an operation be performed, and unexpected conditions develop or are discovered in the course of the operation, it is the duty of the surgeon, in dealing with these conditions, to act on his own discretion, making the highest use of his skill and ability to meet the exigencies which confront him; and, in the nature of things, he must frequently do this without consultation or conference with anyone, except, perhaps, other members of his profession who are assisting him. Emergencies arise; and when a surgeon is called, it is sometimes found that some action must be taken immediately for the preservation of the life or health of the patient, where it is impracticable to obtain the consent of the ailing or injured one, or of anyone authorized to speak for him. In such event, the surgeon may lawfully, and it is his duty to, perform such operation as good surgery demands, without such consent. The case before us, however, does not fall within either of these two classes." In view of the dearth of authority upon this point, attention may profitably be called to the decision of the appellate court in the above case ([1905] 118 Ill. App. 167), which was affirmed on appeal. That court, after alluding by way of illustration to the superior authority which is vested in parents over chiudren or in guardians of the person over those who are insane or imbecile, said: "In a much restricted form it may be said to exist in the marriage relation, which makes the husband the head of the family. This last authority is not, however, supreme in the matter of surgical operations upon the person, and this is really the gist of the decisions in M'Clallen v. Adams (1837) 19 Pick. (Mass.) 333, 31 Am. Dec. 140, and State use of Janney v. Housekeeper (1889) 70 Md. 162, 2 L.R.A. 587, 14 Am. St. Rep. 340, 16 Atl. 382, which are urged on us in argument as showing that the consent of the husband of the appellant was not necessary in the case at bar. These decisions are not authority for the proposition that when a wife is herself incompetent from mental condition intelligently to give or withhold her consent, that the husband's consent is unnecessary, but for the very different proposition that where the wife, competent mentally to decide, assents to and desires a dangerous operation, the surgeon is justified in performing it (if it be in his judgment a proper one) without the further consent of the husband. . . The courts in cases cited supra have decided that a husband has no right in certain circumstances to forbid an operation that a wife wishes to subject herself to. Much more strongly would they deny that 'the gentle restraint' of his wife's person, said to be the right of the husband, extends to compelling her to a capital or major operation without her consent." While not strictly within the scope of this note, attention is called to a case which supports the doctrine of the cases already referred to. In this case, Bakker v. Welsh (1906) 144 Mich. 632, 7 L.R.A. (N.S.) 612, 108 N. W. 94, 8 Ann. Cas. 195, 20 Am. Neg. Rep. 382, it is held that surgeons were not liable for performing an operation upon a minor without first obtaining the consent of his father to the operation. In reaching this conclusion, the court said: "We then come to the question, Are defendants liable in this action because they engaged in this operation without obtaining the consent of the father? Counsel for the plaintiff are very frank with the court, and say in their brief: 'We are unable to aid the court by reference to any decisions in point. We have devoted much time and research to this interesting question, but have been unable to find any decisions of a higher court either supporting or opposing the plaintiff's contention, and we will therefore have to be content by calling the court's attention to such general reasoning as leads us to take the view herein contended for.' They then argue at length and with a good deal of force that, as the father is the natural guardian of the child and is entitled to his custody and his services, he cannot be deprived of them without his consent. We quote: 'We contend that it is wrong in every sense, except in cases of emergency, for a physician and surgeon to enter upon a dangerous operation, or, as in this case, the administration of an anesthetic, conceded to be always accompanied with danger that death may result, without the knowledge and consent of the parent or guardian. It is against public policy and the sacred rights we have in our children that surgeons should take them in charge without our knowledge, and send to us a corpse as the first notice or intimation of their relation to the case.' On the part of defendants, it is contended: (1) Consent of the father was unnecessary. (2) The lack of consent was not the cause of the boy's death, hence not actionable. (3) That, if it were, the action does not survive under the death act. (4) That the action, if any, is in the father, not in the administrator. "We do not think it necessary to a disposition of the case to decide all of the defenses interposed by the defendant. The record shows a young fellow almost grown into manhood, who has been for a considerable period of time, while living with his father, afflicted with a tumor. He has attempted, while at home, to have it removed by absorption. It does disappear, but after a time it reappears. He goes up to a large city, and with an aunt and two sisters, all adults, submits to examination, receives some advice, and goes back to his father with an agreement to return later to receive the report of the expert, who is to make the microscopic examination. He returns accordingly, and with at least some of his adult relatives arranges to have a surgical operation of a not very dangerous character performed. Preparations are made for its performance. There is nothing in the record to indicate that, if the consent of the father had been asked, it would not have been freely given. There is nothing in the record to indicate to the doctors, before entering upon the operation, that the father did not approve of his son's going with his aunt and adult sisters, and consulting a physician as to his ailment, and following his advice. We think it would be altogether too harsh a rule to say that under the circumstances disclosed by this record, in a suit under the statute declared upon, the defendants should be held liable because they did not obtain the consent of the father to the administration of the anesthetic." A. G. S. 1. Making possession of a motor vehicle with the manufacturer's serial numbers removed a penal offense is a valid exercise of the police power. [See note on this question beginning on page 1538.] ERROR to the Municipal Court of Chicago (Richardson, J.) to review a judgment convicting defendant of violating the Motor Vehicle Law. Affirmed. The facts are stated in the opinion Messrs. Fyffe, Ryner, & Dale for plaintiff in error. Messrs. Edward J. Brundage, Attorney General, Edward C. Fitch, Assistant Attorney General, Maclay Hoyne, and Edward E. Wilson, for the People: The police power of the state, upon its exercise by the legislature in the passage of laws for the protection of life, liberty, and property, or laws for the general welfare, has no limitations or restrictions except such as are found in the Constitution. Powell v. Pennsylvania, 127 U. S. 678; Hawthorne v. People, 109 Ill. 302. It is for the legislature to determine when the conditions exist calling for of the court. the exercise of police power to meet existing evils, and when the legislature has acted, the presumption is that the act is a valid exercise of such power. People v. Henning Co. 260 Ill. 562; Hawthorne v. People, 109 Ill. 302; People v. McBride, 234 Ill. 146; People v. Stokes, 281 Ill. 159; Powell v. Pennsylvania, 127 U. S. 678. The legislature may forbid the doing of an act and make its commission criminal without regard to the intent of the doer, and where such intention on the part of the legislature is manifest, the courts must give it effect, although the intention of the doer may have been innocent. McCutcheon v. People, 69 Ill. 601; Farmer v. People, 77 Ill. 322; Byars v. City of Mt. Vernon, 77 Ill. 467; People v. Hatinger, 174 Mich. 333; People v. Emmons, 178 Mich. 128; Mills v. The State, 58 Fla. 74; Beiser v. The State, 9 Ala. App. 72; Lightle v. The State, 5 Okla. Crim. Rep. 259. And where the legislature makes an act criminal, it is the duty of the party to know the law, and he should make inquiry as to what the situation is before acting. McCutcheon v. People, 69 Ill. 601; People v. Spoor, 235 Ill. 230, at p. 232; People v. Nylin, 236 Ill. 19. Where a statute does not make knowledge an element of the offense, the statute is not thereby rendered unconstitutional. Under such a statute, lack of knowledge or good faith is no defense. Farmer v. People, 77 Ill. 322; People v. Robey, 52 Mich. 577; State v. Brown, 144 Pac. 444; State v. Quinn, 131 La. 490; Com. v. Mixer, 207 Mass. 141; State v. Welsh, 145 Wis. 86. One dealing with a subject brought under police regulation assumes the hazards thereof, and must be held to strict conformity with the requirements of the law governing it. People v. Nylin, 236 Ill. 19; City of Chicago v. Truax, Greene & Co. 192 Ill. App. 524; Feeley v. United States, 236 Fed. 903, 905; Feeley v. Melrose, 205 Mass. 329; Wells Fargo Express Co. v. State, 79 Ark. 349. In enforcing police power measures, in the absence of the use of the term "knowingly" therein, it is not necessary that the party charged have actual knowledge of the commission of the offense, or that there be a wrongful intent, because the general rule that criminal intent is the essence of the crime does not apply to an act which is simply malum prohibitum. People v. Werner, 174 N. Y. 132; State v. Burnham, 71 Wash. 199; State v. Nichols, 61 Wash. 142; 1 Wharton's Crim. Law, 11th ed. sec. 108 et seq. pp. 143-146. Thompson, J., delivered the opinion of the court: The plaintiff in error, Harry Johnson, was convicted in the municipal court of Chicago of a violation of § 15b of the Motor Vehicle Law (Hurd's Rev. Stat. 1917, p. 2576), and was sentenced to pay a fine of $200 and costs. He prosecutes this writ of error to reverse the judg ment and sentence of the court. The facts are not in dispute. The plaintiff in error was the general manager of the Commercial Car Unit Company, whose place of business is located in Chicago. The company was engaged in the business of attaching truck units to pleasure car units and making of them commercial trucks. On January 5, 1918, the Ford Motor Company delivered the six new Ford cars to the premises of the Commercial Car Unit Company. The plaintiff in error thereupon ordered one of his workmen to change the motor numbers on these cars. There were seven figures in each of the numbers, which had been stamped on the left-hand side of each of these motors with a steel die by the Ford Motor Company. Following directions of plaintiff in error, the workmen changed the motor numbers of these new Ford cars by hammering out the third and fourth figures and stamping different figures over the same spots. The first two and last three figures in the number were not touched. No explanation is made for changing. the numbers. The only question before us is the constitutionality of said § 15b of the 8 Motor Vehicle Law, which provides: "Any person having in his or her possession any motor bicycle or motor vehicle from which the manufacturer's serial number, or any other manufacturer's trade or distinguishing number or identification mark, has been removed, defaced, covered, or destroyed for the purpose of concealing or destroying the identity of such motor bicycle or motor vehicle shall be liable to a fine of not more than two hundred dollars ($200) or imprisonment in the county jail for a period not to exceed six (6) months, or both." It is urged that this section of the statute violates § 2 of article 2 of the Constitution of this state as well as $ 1 of the 14th Amendment of the Federal Constitution, in that it deprives the defendant of his liberty and property without due process of |