Ratified in 1868, three years after the end of the American Civil War, the 14th Amendment granted citizenship to everyone born on US soil, including formerly enslaved people, and promised all citizens equal protection under the law. Ava DuVernay traces how the amendment has been interpreted, fought over and tested ever since, from Reconstruction to the civil rights era, and examines current efforts to narrow the rights it guarantees, including birthright citizenship. Interviewees include politicians Alexandria Ocasio-Cortez, Jeff Flake, Alex Padilla and Stacey Abrams, legal scholars Sherrilyn Ifill and Robert Chang, and historians Eric Foner and David Blight. A companion piece to DuVernay's acclaimed 13th (2016), which examined the 13th Amendment and mass incarceration, this documentary brings together voices from across the political spectrum to explore one of the most consequential and contested passages in the US Constitution.