Statutory Liens A State statute which gives a lien upon all vessels whether domestic or foreign, and whether engaged in interstate commerce or not, for injuries to persons and property within the State, does not as applied to nonmaritime torts offend the commerce clause, there being no act of Congress in conflict.[897] Nor can the enforcement of a lien for materials used in the construction of a vessel be avoided because the vessel is engaged in interstate commerce.[898] The Police Power and the Subject-Matter of Commerce SCOPE OF THE POLICE POWER "Quarantine regulations are essential measures of protection which the States are free to adopt when they do not come into conflict with Federal action. In view of the need of conforming such measures to local conditions, Congress from the beginning has been content to leave the matter for the most part, notwithstanding its vast importance, to the States and has repeatedly acquiesced in the enforcement of State laws. * * * Such laws undoubtedly operate upon interstate and foreign commerce. They could not be effective otherwise. They cannot, of course, be made the cover for discriminations and arbitrary enactments having no reasonable relation to health * * *; but the power of the State to take steps to prevent the introduction or spread of disease, although interstate and foreign commerce are involved (subject to the paramount authority of Congress if it decides to assume control), is beyond question.[899] * * * State inspection laws and statutes designed to safeguard the inhabitants of a State from fraud and imposition are valid when reasonable in their requirements and not in conflict with Federal rules, although they may affect interstate commerce in their relation to articles prepared for export or by including incidentally those brought into the State and held for sale in the original imported packages."[900] QUARANTINE LAWS In two earlier cases a Missouri statute which prohibited the driving of all Texan, Mexican, and Indian cattle into the state during certain seasons of the year was held void;[901] while a statute making anybody in the State who had Texas cattle which had not wintered north of a certain line liable for damage through the communication of disease from these to other cattle was sustained;[902] as were also the regulations of a sanitary commission which excluded all cattle, horses, and mules, from the State at a certain period when anthrax was prevalent.[903] Reviewing previous cases in the one last cited, the Court declared their controlling principle to be simply whether the police power of the State had been exerted to exclude "_beyond what is necessary for any proper quarantine_," a question predominantly of fact, and one therefore to be determined for each case with only general guidance from earlier decisions.[904]