The federal statute in question, the Locomotive Inspection Act (LIA), 49 U.S.C. § 20701 et seq., was passed by Congress in 1915. (indianainjuryblog.com)
The five statutes in question were struck down because the State of California, helped by the California Teachers Association, could not show that the laws in any way supported the education of children. (educationnext.org)
The problem with the plaintiffs» argument, according to the court, was that it did not prove that the statutes in question disproportionately harmed a particular class of children. (educationnext.org)