An entry in this variable indicates that the Court either declared unconstitutional an act of Congress; a state or territorial statute, regulation, or constitutional provision; or a municipal or other local ordinance. In coding this variable we consulted several sources. Most helpful was the Congressional Research Service’s Constitution of the United States of America: Analysis and Interpretation (CONAN) (congress.gov/constitution-annotated) and the appendix to volume 131 of the U.S. Reports.

Note that the Court need not necessarily specify in so many words that a law has been declared unconstitutional. That commonly occurred in legacy decisions (pre-1946); e.g., Willcox v. Consolidated Gas Co. of New York, 53 L Ed 382 (1909).

The summary frequently, though not invariably, will indicate such action in its statement of the Court’s holdings. Hence, where such action may have occurred, it may be necessary to read carefully the opinion of the Court to determine whether an entry should be made in this variable.

Where federal law preempts a state statute or a local ordinance, unconstitutionality does not result unless the Court’s opinion so states. Nor are administrative regulations the subject of declarations of unconstitutionality unless the declaration also applies to the law on which it is based. Also excluded are federal or state court-made rules; e.g., Virginia Supreme Court v. Friedman, 487 U.S. 59 (1988).