If you watched the opening ceremonies for the Smithsonian Institution’s National Museum of African American History and Culture on the National Mall on Saturday, you may have wondered why Chief Justice John Roberts Jr. addressed the crowd, along with dignitaries from Stevie Wonder to former First Lady Laura Bush.

It was a rare broadcast appearance for the chief justice, and he spoke about the U.S. Supreme Court’s crucial role—both negative and positive—in the history of African American life.