President Obama warned in a speech last month that the fall campaign season will see "a flood of attack ads run by shadowy groups with harmless-sounding names," which will "spend unlimited amounts of money to influence our elections." The midterm could amount to nothing less, he added, than "the corporate takeover of our democracy." The president's speechwriters may well have had Steven Law in mind, or at least they should have. He is the president and CEO of American Crossroads, a new independent outfit that will spend more than $50 million this year—almost all from large individual (not corporate) donations—on...