This month marks the 150th anniversary of the Constitution as we know it — the glorious, flawed, unexpected moment when our basic law was transformed into a charter of human rights. Its glories define us. But so do its flaws. 

I refer to the 14th Amendment, whose ratification was certified on July 28, 1868. 

It shapes almost every issue we debate today: immigration, racial and gender equality, voter suppression, free speech, corporations and federal power. Its history destroys the notion that freedom grew steadily over time — that the founders bestowed liberty on white men, which was gradually extended to others. Rather, the amendment reinvented freedom. It established birthright citizenship, required “due process” and “equal protection” of the law for everyone, and put the federal government in the business of policing liberty. It removed race and ethnicity from the legal definition of American identity.

Before the 14th Amendment, the Bill of Rights protected almost no one. In Barron v. Baltimore, Chief Justice John Marshall wrote for a unanimous Supreme Court in 1833 that those original amendments restrained only the federal government, not the states, and so did not guarantee individual freedoms. Through the incorporation doctrine, the 14th made the Bill of Rights apply to the states, giving those first amendments the powerful role they play today. And we owe this monumental amendment to the self-assertion of black people.