Justice Stone would have reversed. He accepted that Congress may, within its constitutional authority, make a federal alien-registration system exclusive. But he maintained that courts should not infer such a major withdrawal of state police power from vague implications rather than from a clear congressional command or an unmistakable conflict between state and federal law. Chief Justice Hughes and Justice McReynolds joined his opinion.
In his view, Pennsylvania’s statute was a valid exercise of the state’s police power when enacted. After lawful entry, resident aliens remain subject to generally valid state regulation, including reasonable alien-specific measures. The state had a legitimate interest in identifying aliens within its borders and knowing their whereabouts to enforce state laws protecting persons, property, and public order.
The federal and state statutes could, Justice Stone argued, operate together. Compliance with Pennsylvania’s annual registration and identification-card rules neither prevented compliance with the federal law nor interfered with federal immigration, naturalization, deportation, defense, or foreign-relations functions. The federal law’s confidentiality provision also allowed information to be shared with state agencies upon federal approval.
Justice Stone criticized the majority’s reliance on the phrase that Congress had “occupied the field.” Every federal statute occupies some field, he reasoned; the real question is how far the field extends. Neither the statute’s text nor its legislative history stated that Congress meant to eliminate state registration laws, despite Congress’s awareness that many states had such measures. In the absence of direct and positive conflict, he would have allowed Pennsylvania to retain its otherwise constitutional law.