“ When the penalty is contrasted with the overcharge possible in any instance it of course seems large, but, as we have said, its validity is not to be tested in that way. When it is considered with due regard for the interests of the public, the numberless opportunities for committing the offense, and the need for securing uniform adherence to established passenger rates, we think it properly cannot be said to be so severe and oppressive as to be wholly disproportioned to the offense or obviously unreasonable. ”

“ By a statute of Arkansas, regulating rates for the transportation of passengers between points within the state, any railroad company that demands or collects a greater compensation than the statute prescribes is subjected 'for every such offense' to a penalty of 'not less than fifty dollars nor more than three hundred dollars and costs of suit, including a reasonable attorney's fee,' and the aggrieved passenger is given a right to recover the same in a civil action. ”

“ It is true that the imposition of severe penalties as a means of enforcing a rate, such as was prescribed in this instance, is in contravention of due process of law, where no adequate opportunity is afforded the carrier for safely testing, in an appropriate judicial proceeding, the validity of the rate-that is, whether it is confiscatory or otherwise before any liability for the penalties attaches. ”