521 U.S. 507 (U.S. Supreme Court 1997)
City of Boerne v. Flores is a foundational constitutional law case that sharply defines the boundary between Congress's power to enforce constitutional rights and the judiciary's power to interpret those rights.
Does Congress have authority under Section 5 of the Fourteenth Amendment to impose RFRA's strict-scrutiny standard on state and local laws that substantially burden religious exercise, thereby redefining the scope of Free Exercise protections recognized by the Court?
Congress's power under Section 5 of the Fourteenth Amendment is remedial and preventive: it may enact "appropriate legislation" to deter or remedy constitutional violations as the Court has defined them, but it may not alter the substantive meaning of the rights guaranteed by the Fourteenth Amendment. Such legislation must exhibit congruence and proportionality between the constitutional injury to be prevented or remedied and the means adopted. Under Employment Division v. Smith, neutral, generally applicable state laws that incidentally burden religion ordinarily do not violate the Free Exercise Clause and need not satisfy strict scrutiny.
RFRA, as applied to states and their political subdivisions, exceeds Congress's Section 5 enforcement power and is unconstitutional. Congress may not, through RFRA, mandate strict scrutiny for all state and local laws that substantially burden religious exercise. The judgment of the Fifth Circuit was reversed.
City of Boerne v. Flores is the seminal modern case delimiting Congress's Section 5 power and inaugurating the congruence-and-proportionality test. The decision reinforces judicial supremacy in constitutional interpretation and significantly constrains Congress from imposing broad substantive standards on state and local governments under the guise of enforcement. For religious liberty, Boerne restored Smith's rule for state and local conduct, while leaving RFRA in force against the federal government (a point later reflected in cases such as Gonzales v. O Centro). In response to Boerne, Congress enacted the Religious Land Use and Institutionalized Persons Act (RLUIPA) under the Spending and Commerce Clauses to target specific contexts (land use and institutionalized persons). Beyond religion, Boerne's framework governs a host of Section 5 cases—invalidating some statutes (e.g., ADEA suits against states in Kimel; ADA Title I damages in Garrett) and sustaining others with robust records and tailoring (e.g., FMLA family-care provision in Hibbs; access-to-courts applications of ADA Title II in Tennessee v. Lane).