Following the pattern of the Necessary and Proper Clause of Article I, Section 8, the enforcement clause of the Fourteenth Amendment grants to Congress the power to pass legislation directed at effectuating the provisions of Sections 1 through 4 of the amendment. Like the enforcement clauses of the two other Reconstruction Amendments (the Thirteenth and the Fifteenth), as well as those found in the Nineteenth, Twenty-third, Twenty-fourth, and Twenty-sixth Amendments, Section 5 delegates to Congress a power in addition to those listed in Article I, Section 8, of the Constitution.

One specific purpose of the Fourteenth Amendment when Congress proposed it in 1866 was to ensure that Congress had adequate power to adopt the Civil Rights Act of that year, of which the current 42 U.S.C. § 1981 is a descendant. That act prohibited state legislation—specifically, the notorious “Black Codes”—that denied blacks certain rights afforded to whites, including the power to make and enforce contracts.

A significant limitation in the text of Section 5 is that Congress is authorized only to “enforce, by appropriate legislation” the provisions of the Fourteenth Amendment. Justice William J. Brennan Jr.’s opinion in Katzenbach v. Morgan (1966) suggested that Section 5 might also give Congress authority to define the substantive scope of the rest of the Fourteenth Amendment, but this interpretation seems at odds with the text and history of Section 5, and more recent opinions of the Supreme Court have rejected it. As early as 1883 in The Civil Rights Cases, the Court declared that because the prohibitions of Section 1 of the amendment reached only actions committed by the state or its agents, Congress was not empowered to legislate against the discriminatory actions of private individuals. More recently, in City of Boerne v. Flores (1997), the Court struck down as unconstitutional the Religious Freedom Restoration Act, in which Congress tried to use Section 5 to overturn an earlier Supreme Court decision defining the scope of the Free Exercise Clause with respect to the states. In doing so, the Court explicitly rejected Justice Brennan’s suggestion in Morgan that Section 5 allows Congress to expand the meaning of the rest of the amendment. Thus, for Congress to invoke its power under Section 5, the proposed legislation must be aimed at remedying or preventing actions that would violate some prohibition within the Fourteenth Amendment.

The legislation cannot be aimed at changing the scope of the amendment.

On the other hand, the Supreme Court has declared that Congress may, as a prophylactic matter, ban state actions that it has found generally to violate the Fourteenth Amendment, even if in some instances they might not. A classic example is the literacy test for voting. See Oregon v. Mitchell (1970). In theory, a state could use such a test in a constitutional way, but Congress determined that these tests were so commonly abused that they should be banned across the board, and the Court upheld this ban. The law was aimed at preventing actual and potential violations of the Constitution; it did not change the Constitution’s substantive meaning and guarantees.

In City of Boerne, the Supreme Court declared that there must be a “proportionality” and “congruence” between the statute “and the legitimate end to be achieved.” It follows that, before Congress invokes its Section 5 authority, it must ascertain that the actions it is concerned about do in fact violate the protections within the Fourteenth Amendment and that legislation remedying such violations has a “proportionality” and a “congruence” in accomplishing the remedy. This, in turn, requires a careful analysis of the rest of the Fourteenth Amendment and the scope of its guarantees.

For instance, there must be “state action.” Section 5 gives Congress no authority to legislate with respect to the private sector because, the Court has held, there can be no Section 1 violation without state action. The Civil Rights Cases. Likewise, with respect to religious discrimination, the state action must amount to intentional discrimination. The Court found in City of Boerne that laws that are neutral in text and intention and that have only a disproportionate effect on a religious group are beyond Congress’s authority to prohibit. The same kinds of distinctions and limitations apply with respect to other anti-discrimination legislation. For example, because the disabled are not “a suspect classification,” state discrimination against the disabled violates the Fourteenth Amendment only if it is “irrational.” Thus, the Court has held in Board of Trustees of the University of Alabama v. Garrett (2001) that Section 5 gives Congress authority only to ban irrational state employment discrimination against the disabled, although in the closely disputed case of Tennessee v. Lane (2004), the Court upheld Congressional abrogation of state sovereign immunity in actions brought under the Americans with Disabilities Act where Congress was seeking to ensure the right of access to the courts for persons with disabilities.