"To say that only those businesses affected with a public interest may be regulated is but another way of stating that all those businesses which may be regulated are affected with a public interest"

Harlan Stone collapses the once-crucial distinction between “private” businesses and those “affected with a public interest.” The phrase had been used to cordon off a special class, public utilities, common carriers, grain elevators, whose rates and practices could be supervised. Stone points out the circularity: if only businesses touched by public interest may be regulated, and the only ones we regulate are those we say are touched by public interest, the label explains nothing. It merely restates the outcome.

The deeper move is methodological. Rather than treating “public interest” as a metaphysical property that some industries possess, Stone treats it as a legislative judgment about when private conduct has sufficient social consequences to justify oversight. In a complex economy, pricing, labor relations, health, safety, and market power in almost any sector can spill over onto the public. That fluid reality makes rigid categories unhelpful. The meaningful inquiry is not whether a business belongs to a preapproved class, but whether the regulation serves a legitimate end and bears a reasonable relation to that end.

This reframing undercuts the old liberty-of-contract era that policed economic regulation through narrow classifications. It substitutes deference and pragmatism: elected bodies may regulate where public welfare, security, or order are genuinely implicated, whether the subject is milk prices, ticket brokers, or utilities. “Public interest” becomes the conclusion of analysis, not its premise, a recognition that the community bears real costs or risks if the activity is left wholly to private discretion.

Stone’s interpretation does not declare that every business must be regulated. It insists that no business is immune in principle if its operations create public consequences. The judiciary’s role is to test reasonableness and fit, not to freeze the economy into formal boxes. By exposing the tautology, Stone freed constitutional doctrine to track actual public needs, shifting the focus from taxonomy to justification and from abstract labels to concrete evidence of how private enterprise affects the broader community.