On a July day in 2006, the entire Republican caucus was invited to hear a private debate in a meeting room in the Capitol. Scores of GOP members attended, including House Speaker Dennis Hastert. At issue was whether the federal government should continue to have control over every election-law change in sixteen states, including Texas, California, Florida, and South Carolina. Federal power over the states was set to expire. On one side of the debate was lawyer Mike Carvin, who argued that federal oversight should end. Carvin’s opponent arguing for continued federal power to review election changes like voter ID...