The living constitution

[The Voting Rights Act's] "Section 4's formula is unconstitutional in light of current conditions." Roberts for the majority (including Scalia) in Shelby County. Scalia in oral arguments on the DOMA case: "I'm curious, when did it become unconstitutional to exclude homosexual couples from marriage? 1791? 1868? When the Fourteenth Amendment was adopted?... Well, how am I supposed to how to decide a case, then, if you can't give me a date when the Constitution changes?" I'm curious, Justice Scalia: when did the evolving standards of the living constitutional text of Amendment 15 section 2 change to make the VRA Section 4 unconstituional? Can you give me a date on that?