Back in 2005, when Democrats in Congress fought to preserve their right to filibuster against George W. Bush's judicial nominees, they spoke in unison about how Republicans were "changing the rules in the middle of the game," a slogan they had tested with focus groups like a catchphrase for breakfast cereal. The idea was to turn an arcane question of process into a basic issue of fairness in the public mind, and it worked. Now, five years later, Republicans reeling from their health care...