Antitrust populists increasingly call on the government to “break up big tech.” But antitrust enforcers would face heavy evidentiary burdens if they sought to break a company up on the premise that a long-consummated merger was unlawful from the outset and should have been blocked years ago....

In 1981, while in the FTC's Bureau of Consumer Protection, two of the authors were instrumental in initiating the FTC's fraud program, relying on Section 13(b)'s authority to obtain a permanent injunction to seek equitable relief, including asset freezes and consumer redress. The fraud program...