Justice John Marshall Harlan (majority): “Looking alone at the words of the statute for the purpose of ascertaining its scope and effect, and of determining its validity, we hold that there is no such connection between interstate commerce and membership in a labor organization as to authorize Congress to make it a crime against the United States for an agent of an interstate carrier to discharge an employee because of such membership on his part. If such a power exists in Congress it is difficult to perceive why it might not, by absolute regulation, require interstate carriers, under penalties, to employ, in the conduct of its interstate business, only members of labor organizations, or only those who are not members of such organizations—a power which could not be recognized as existing under the Constitution of the United States.”

Justice Joseph McKenna (dissenting): “It also seems to me to be an oversight of the proportions of things to contend that, in order to encourage a policy of arbitration between carriers and their employees which may prevent a disastrous interruption of commerce, the derangement of business, and even greater evils to the public welfare, Congress cannot restrain the discharge of an employee, and yet can, to enforce a policy of unrestrained competition between railroads, prohibit reasonable agreements between them as to the rates at which merchandise shall be carried.”