A court determines whether a statute is severable (or separable) in order to decide one of two different questions: When part of the law is unconstitutional, should the court hold the entire statute invalid, or merely the offending part? When the law can be applied validly to the litigant in court, should the court nonetheless hold the law invalid because it is capable of being applied unconstitutionally to others?
The first question was presented in carter v. carter coal co. (1936). Congress had regulated coal prices and the wages and hours of coal miners. After holding the wage and hour regulations invalid, the Supreme Court posed the severability issue in the usual way, as a question of legislative intent : if Congress had known the wage and hour provisions would be held invalid, would it still have regulated prices? Congress had stated plainly that if any part of the coal act were held invalid, the rest of the law remained effective. Nonetheless, the Court said, the price controls were so closely related to the labor provisions that Congress would not have enacted them alone. The price controls were thus invalid, whether or not they would have been valid if considered by themselves. The issue of severability calls into play the same kind of judgment employed in judicial review of the constitutionality of legislation.
Carter involved a federal statute. When a state law presents a similar question of severability, the Supreme Court ordinarily leaves that question to the state courts. However, a state statute may present the Court with the second type of severability issue. When a state law is invalid on its face—for example, under the first amendment doctrine of overbreadth—the Court refuses to enforce the law because of its potential unconstitutional application to persons not in court. This practice moderates the effect of the rule denying a litigant standing to raise other persons' legal rights.
Kenneth L. Karst
Monaghan, Henry P. 1982 Overbreadth. Supreme Court Review 1982:1–39.
Note 1984 Severability of Legislative Veto Provisions: A Policy Analysis. Harvard Law Review 97:1182–1197.
Stern, Robert L. 1937 Separability and Separability Clauses in the Supreme Court. Harvard Law Review 51:76–128.