The enactment and enforcement by the States of quarantine laws, whether with reference to persons or to property, has given rise to numerous cases in which their constitutionality as tested by the commerce clause has been considered. Quarantine laws are, of course, but a variety of police laws, and their validity is determined as such. That is to say, as declared in Railroad Co. v. Husen,95 "while for the purpose of self-protection it [the State] may establish quarantine and reasonable inspection laws, it may not interfere with transportation into or through the State, beyond what is absolutely necessary for its self-protection."In Railroad Co. v. Husen was in question an act of the State of Missouri which provided that. "No Texas, Mexican, or Indian cattle shall be driven or otherwise conveyed into or remain in any county in this State between the first day of March and the first day of November in each year by any person or persons whatever." This act, claimed to be a quarantine measure, the court held void, saying : "The statute of Missouri is a plain intrusion upon the exclusive domain of Congress. It is not a quarantine law. It is not an inspection law. It says to all natural persons and to all transportation companies, 'You shall not bring into the State any Texas cattle or any Mexican cattle or Indian cattle, between March 1 and December [November] 1 in any year, no matter whether they are free from disease or not; no matter whether they may do an injury to the inhabitants of the State or not.' . . . Such a statute, we do not doubt, it is beyond the power of a State to enact."

In Morgan's L. & T. R., etc., Co. v. Louisiana Board of Health96 a state law was upheld as a reasonable quarantine measure, though admitted to be, in a measure, a regulation of commerce.

94 209 U. S. 251; 28 Sup. Ct. Rep. 485; 52 L. ed. 778.

95 95 U. S. 465; 24 L. ed. 527.

96 118 U. S. 455; 6 Sup. Ct. Rep. 1114; 30 L. ed. 237.

In Rasmussen v. Idaho97 was sustained a law of a State authorizing the Governor thereof, when he had reason to believe that there is an epidemic of infectious disease of sheep in localities outside of the State, to investigate the matter, and if he finds that the disease exists, to make a proclamation declaring such localities infected and prohibiting the introduction therefrom of sheep into the State, except under such restrictions as may seem proper. Distinguishing the act from that held void in the Husen case, the court say: "It will be perceived that this is not a continuous act, operating year after year irrespective of any examination as to the actual facts, but is one contemplating in every case investigation by the chief executive of the State before any order of restraint is issued. Whether such restraint shall be total or limited, and for what length of time, are matters to be determined by him upon full consideration of the condition of the sheep in the localities supposed to be affected. The statute was an act of the State of Idaho, contemplating solely the protection of its own sheep from the introduction among them of an infectious disease, and providing for only such restraints upon the introduction of sheep from other States as in the judgment of the State was absolutely necessary to prevent the spread of disease. The act therefore is very different from the one presented in Hannibal & St. J. R. Co. v. Husen (95 U. S. 465; 24 L. ed. 527) and is fairly to be considered a purely quarantine act, and containing within its provisions nothing which is not reasonably appropriate therefor."

In Smith v. St. Louis, etc., Ry. Co.98 were sustained quarantine regulations established by the governor of the State on recommendation of a live stock commission in pursuance of a law whereby the importation of all cattle from the State of Louisiana for a certain period was prohibited, because the commission had reason to believe that anthrax had or was liable to break out in that State the importing of cattle from south of the thirty-sixth parallel of north latitude between certain dates, unless first kept for ninety days at some State north of that .parallel or unless a certificate of freedom from contagious disease had been obtained from the state veterinary sanitary board. These provisions, were, in view of the surrounding circumstances, held to be reasonable sanitary precautions.

In Reid v. Colorado99 was sustained a state law prohibiting

97 181 U. S. 108: 21 Sup. Ct. Rep. 594; 45 L. ed. 820. 98 181 U. S. 248; 21 Sup. Ct. Rep. 603; 45 L. ed. 847. 99 187 U. S. 137; 23 Sup. Ct. Rep. 92; 47 L. ed. 108.

In Compagnie Francaise, etc. v. State Board of Health of Louisiana1 the subject of state quarantine was again carefully considered, and especially in its relation to the existing immigration and quarantine acts of the General Government. These federal laws, it was held, were not intended to and did not abrogate the existing state quarantine systems.