Continued validity of the remainder of a statute once a portion of that statute has been declared invalid (usually because it violates the Constitution). Also known as “severability of statutes” and “divisibility of statutes.”
Frequently, when the Supreme Court declares a statutory provision unconstitutional, the statute at issue contains other unchallenged provisions. The remainder of the statute may be constitutional and could well be upheld as a separate statute. In such a situation, the Court must decide whether the remainder of the statute can be severed from the provision it has found unconstitutional; that is, the Court must decide whether the statute should remain in force even though a part of that statute is no longer valid. If the challenged statute is not severable, the entire statute must be invalidated. If the statute is severable, the unchallenged portion of the statute can remain in effect.
Ordinarily, the Court decides whether a statute is separable based on its perception of Congress’s intent. In particular, the Court attempts to decide whether the Congress that enacted the statute would have wanted the portion of the statute that was not declared unconstitutional to remain in effect despite the Court’s invalidation of the remainder of the statute. Often, Congress expressly includes in statutes a separability clause providing that the statute is separable and should remain in effect even if one portion of the statute is declared unconstitutional. When Congress includes such a clause in a statute, the Court presumes the statute is separable. However, the Court does not presume that the absence of such a clause means that the statute is not separable. Congress can include a clause that specifies that certain statutory provisions are not severable.
The separability of state statutes is a matter of state law, so state supreme courts have the ultimate power to decide whether partially invalidated state statutes are separable. The separability of federal statutes is a matter of federal law, and the Supreme Court has the power to make final decisions regarding the separability of federal statutes. The Supreme Court rarely explicitly discusses the issue of separability and rarely declares an entire statute invalid because a portion of the statute violates the Constitution. However, the Court has explicitly addressed the question of the separability of federal statutes that include a legislative veto provision of the type declared unconstitutional in Immigration and Naturalization Service v. Chadha
Singer, Norman J. Statutes and Statutory Construction. 5th ed. Deerfield, Ill.: Clark, Boardman, Callaghan, 1993.
Immigration and Naturalization Service v. Chadha