Pierce Butler, Di Santo v. Commonwealth of Pennsylvania…
“ The Congress has complete and paramount authority to regulate foreign commerce and, by appropriate measures, to protect the public against the frauds of those who sell these tickets and orders. The sales here in question are related to foreign commerce as directly as are sales made in ticket offices maintained by the carriers and operated by their servants and employees. The license free and other things imposed by the act on plaintiff in error, who initiates for his principals a transaction in foreign commerce, constitute a direct burden on that commerce. ”
