Chief Justice John Roberts cast the deciding vote against the Trump administration’s attempt to add a citizenship question to the 2020 census. But he only did it after changing his position behind the scenes, sources told CNN in this exclusive report. Roberts was all set to join the Supreme Court’s four conservative justices and rule for the administration. But he changed his mind — and his vote — because he believed the administration’s rationale for adding the citizenship question was contrived. Roberts’ action in the case proves he’s getting less predictable as he becomes the de facto swing vote on the divided court, says CNN legal analyst & Supreme Court biographer Joan Biskupic.