A Supreme Court justice will conduct a same-sex marriage ceremony for the first time ever on Saturday. Justice Ruth Bader Ginsburg is set to officiate at the wedding of her longtime friend Michael Kaiser, the president of the John F. Kennedy Center for the Performing Arts, and his fiance John Roberts (the economist, not the Chief Justice) at the arts center in Washington, D.C. The wedding is not a gala event, a spokesperson for the center said, but its guest list has more than 200 people on it. Ginsburg, who turned 80 this year, was part of the Supreme Court majority that handed down its landmark decision striking down a part of the federal Defense of Marriage Act and paving the way for married same-sex couples to get the same federal benefits as straight ones. At oral arguments in the case earlier in the year, she famously termed the granting of limited marital benefits to same-sex couples a kind of "skim-milk marriage."