There is nothing in the provisions of the act of Louisiana providing for the appointment of two gaugers of coal and coke boats which can properly be considered as regulations of commerce, in conflict with the power vested in congress over the subject. They only prescribe the rule by which the capacity of the carrying vessels of coal and coke can be determined, and the weight of the coal or coke carried ascertained, which may be readily done at any time. They were adopted for the convenience of the owners of the boats and loads. They are properly to be regarded as a part of those innumerable police regulations which every state may enact for the convenience and comfort of its inhabitants in the conduct of their business. They do not add to the increase or to the diminution of the productions of the state or to the facility of their transportation or of their loading or landing. They may in some cases in a slight degree affect commerce, but not in such an extent or sense as to be properly designated as regulations of commerce.
As this court said in Smith v. Alabama, 124 U.S. 473, 8 Sup. Ct. 564: 'There are many cases where the acknowledged powers of a state may be exerted and applied in such a manner as to affect foreign or interstate commerce without being intended to operate as commercial regulations. If their operation and application in such cases regulate such commerce, so as to conflict with the regulation of the same subject by congress, either as expressed in positive laws or implied from the absence of legislation, such legislation on the part of the state, to the extent of that conflict, must be regarded as annulled. To draw the line of interference between the two fields of jurisdiction, and to define and declare the instances of unconstitutional encroachment, is a judicial question often of much difficulty, the solution of which, perhaps, is not to be found in any single and exact rule of decision. Some general lines of discrimination, however, have been drawn in varied and numerous decisions of this court. It has been uniformly held, for example, that the states cannot by legislation place burdens upon commerce with foreign nations or among the several states.' 'But, upon an examination of the cases in which they were rendered,' the court added, speaking from Sherlock v. Alling, 93 U.S. 99, 'it will be found that the legislation adjudged invalid imposed a tax upon some instrument or subject of commerce, or exacted a license from parties engaged in commercial pursuits, or created an impediment to the free navigation of some public waters, or prescribed conditions in accordance with which commerce in particular articles or between particular places was required to be conducted. In all the cases the legislation condemned operated directly upon commerce, either by way of tax upon its business, license upon its pursuit in particular channels, or conditions for carrying it on.' In that case it was held that a statute of Indiana, giving a right of action to the personal representatives of the deceased where his death was caused by the wrongful act or omission of another, was applicable to the case of a loss of life occasioned by a collision between steamboats navigating the Ohio river engaged in interstate commerce, and did not amount to a regulation of commerce in violation of the constitution of the United States. On this point the court said (page 103): 'General legislation of this kind, prescribing the liabilities or duties of citizens of a state, without distinction as to pursuit or calling, is not open to any valid objection because it may affect persons engaged in foreign or interstate commerce. Objection might, with equal propriety, be urged against legislation prescribing the form in which contracts shall be authenticated, or property descend or be distributed on the death of its owner, because applicable to the contracts or estates of persons engaged in such commerce. In conferring upon congress the regulation of commerce, it was never intended to cut the states off from legislating on all subjects relating to the health, life, and safety of their citizens, though the legislation might indirectly affect the commerce of the country. Legislation, in a great variety of ways, may affect commerce and persons engaged in it without constituting a regulation of it within the meaning of the constitution.