Barack Obama is gunning for a confrontation with the Supreme Court, and Chief Justice John Roberts has signaled that he welcomes the fight. Last week, the chief justice described the president’s State of the Union condemnation of the Citizens United decision as “very troubling” and complained that the speech had “degenerated to a political pep rally.” Roberts was making an argument about etiquette--dissent was fine, he said, but Obama had somehow transgressed the boundaries of civilized discourse by delivering his attack to a captive audience. But he was implicitly making a political argument as well. That is, Roberts seems to...