How did City of Boerne v. Flores limit the reach of the Religious Freedom Restoration Act?

In City of Boerne v. Flores (1997), the U.S. Supreme Court ruled that the Religious Freedom Restoration Act (RFRA) was unconstitutional as applied to state and local governments.1

While Congress intended for the RFRA to apply broadly to all levels of government, the Court held that Congress exceeded its enforcement powers under Section 5 of the Fourteenth Amendment. The Court determined that Congress has the power to enact "remedial and preventive measures" to enforce constitutional rights, but it cannot substantively redefine those rights or impose such a broad mandate that it intrudes upon the traditional authority of the states. Because the RFRA lacked evidence of widespread religious bigotry by state governments and was deemed "out of proportion" to any legitimate remedial object, the Court invalidated its application to the states.1

Consequently, the RFRA remains valid only regarding federal actions. This limitation is significant in cases like Burwell v. Hobby Lobby Stores, Inc., where the Court applied the RFRA specifically to a federal regulation.12