The Granger law remained in force until 1878. Its constitutionality was tested by the railroad companies in the Supreme Court of the United States, but this high tribunal held that rate-making was a legislative and not a judicial function, that it was within the province of the State legislature to prescribe rates for the transportation of passengers and freight wholly within the State, and that for protection against abuses by legislatures the people must resort to the polls, and not to the courts. The Granger laws have been and are still severely criticised by those opposed to the principle of State control and by the ignorant. It is nevertheless true that those laws were moderate, just and reasonably well adapted to remedy the evils of which the public complained. It has been the policy of most railroad men to attack them as crude, intensely radical and socialistic. The obloquy heaped upon them was the work of designing men who desired to continue their impositions upon the people. Mr. Charles Francis Adams, however, admits that the Granger method was probably as good a method as could have been devised of approaching men who had thoroughly got it into their heads that they, as common carriers, were in no way bound to afford equal facilities to all, and, indeed, that it was in the last degree absurd and unreasonable to expect them to do so. The Iowa law was imperfect in detail, and yet its enactment proved one of the greatest legislative achievements in the history of the State. It demonstrated to the people their ability to correct by earnestness and perseverance the most far-reaching public abuses and led to an emphatic judicial declaration of the common-law principle that railroads are highways and as such are subject to any legislative control which may be deemed necessary for the public welfare.