From what has gone before, it is clear that while classification of persons and businesses for purposes of regulation is not prohibited by the requirement of equal protection of the law, these classifications must in every case be reasonable ones. In Gulf, etc., Ry. Co. v. Ellis,28 already cited, it is declared: "It is apparent that the mere fact of classification is not sufficient to relieve a statute from the reach of the equality clause of the Fourteenth Amendment, and that in all cases it must appear not only that a classification has been made, but also that it is one based upon some reasonable ground, - some difference which bears a just and proper relation to the attempted classification, - and is not a mere arbitrary selection."
25 The opinion declares: "A mere statute to compel the payment of indebtedness does not come within the scope of police regulations. The hazardous business of railroading carries with it no special necessity for the prompt payment of debts. That is a duty resting upon all debtors, and while, in certain cases, there may be a peculiar obligation which may be enforced with penalties, yet nothing of that kind springs from the mere work of railroad transportation. Statutes have been sustained giving special protection to the claims of laborers and mechanics, but no such idea underlies this legislation. It does not aim to protect the laborer or mechanic alone, for its benefits are conferred upon every individual in the State, rich or poor, high or low, who has a claim of the character described. It is not a statute for the protection of particular classes of individuals supposed to need protection, but for the punishment of certain corporations on account of their delinquency. Neither can it be sustained as a proper means of enforcing the payment of small debts, and preventing any unnecessary litigation in respect to them, because it does not impose the penalty in all cases where the amount in controversy is within the limit named in the statute. Indeed, the statute arbitrarily singles out one class of debtors, and punishes it for a failure to perform certain duties, - duties which are equally obligatory upon all debtors; a punishment not visited by reason of the failure to comply with any proper police regulations, or for the protection of the laboring classes, or to prevent litigation about trifling matters, or in consequence of any special corporate priviliges bestowed by the State. Unless the legislature may arbitrarily select one corporation or one class of corporations, one individual or one class of individuals, and visit a penalty upon them which is not imposed upon other guilty of like delinquency, this statute cannot be sustained."
26 165 U. S. 150; 17 Sup. Ct. Rep. 255; 41 L. ed. 666.
Thus in Connolly v. Union Sewer Pipe Co.27 a discrimination made by a state anti-trust law exempting from its operations agricultural products or live stock in the hands of the producer or raiser, was held a denial of the equal protection of the laws. In its opinion the earlier decisions in point are carefully reviewed and distinguished. "With reference to the specific law in question the court say: "To declare that some of the class engaged in domestic trade or commerce shall be deemed criminals if they violate the regulations prescribed by the State for the purpose of protecting the public against illegal combinations formed to destroy competition and to control prices, and that others of the same class shall not be bound to regard those regulations, but may combine their capital, skill, as acts to destroy competition and to control prices for their special benefit, is so manifestly a denial of the equal protection of the laws that further or extended argument to establish that position would seem to be unnecessary." 28