Some scholars see the 14th Amendment’s ambiguity as a weakness. The historian Stephen Kantrowitz argues that “the amendment’s failure to specify equality of political rights would haunt the next century of American history.” In addition, the Supreme Court interpreted the 14th Amendment narrowly during the late 19th century. In a series of rulings that included Plessy v. Ferguson in 1896, which established the doctrine of “separate but equal,” the Supreme Court interpreted the 14th Amendment in a way that did not require the federal government to protect blacks from violence and allowed seemingly race-neutral laws to be applied in unequal ways.

By the turn of the century, black disenfranchisement was nearly complete in the South. In a letter to Harper’s Weekly in 1904, a Georgian declared that “the vast majority of Southern Negroes today do not even know that they are entitled to vote.”

During the civil rights era beginning in the 1950s, however, the Supreme Court reversed course. It found sizable new meanings in the 14th Amendment, holding that it guaranteed desegregated public schools, permitted interracial marriage and ensured equal political representation at the state level. The 14th Amendment also served as the basis for decisions striking down policies that discriminated against pregnant women and denied funding for undocumented children to attend public schools in the 1970s and 1980s. Section 5 of the 14th Amendment gave Congress “power to enforce, by appropriate legislation, the provisions of this article.”

An even broader interpretation of the 14th Amendment may reshape American society in the 21st century. In Zadvydas v. Davis in 2001, the Supreme Court ruled that indefinite government detention of aliens violated the Constitution’s due process clause. More recently, Obergefell v. Hodges in 2015 led to the overturning of states’ bans on gay marriage. The court cited the due process clause of the 14th Amendment in the majority opinion, arguing that “the fundamental liberties protected by the 14th Amendment’s due process clause extend to certain personal choices central to individual dignity and autonomy, including intimate choices defining personal identity and beliefs.”

In the last 50 years, the Supreme Court’s evolving interpretations of the 14th Amendment have led to an expansion of civil rights. Its decisions have also produced a system of federalism that significantly differs from that of 1868 through the reallocation of power from the states to the federal government. Thanks to the 14th Amendment, with its plain text authorizing Congress to act in perpetuity, the contours of our federal system continue to shift.

The question remains: How will the Supreme Court interpret the rights promised by this critical amendment in future cases of national importance? We can only hope that, in the words of Frederick Douglass, it will continue to “give full freedom to every person without regard to race or color in the United States.” While 150 years have passed since the ratification of the 14th Amendment, it is not too late to give this powerful document its due.