Twenty-seven years ago I took my law-school antitrust course, from a fledgling assistant professor who had just left the Federal Trade Commission. My performance was adequate, earning one of the better grades in the course, but not spectacular. Unspectacular enough that afterwards the professor said it disappointed him. In retrospect, I think I under-performed because I was a soon-to-be economist as well as a budding lawyer. Like many people back then, I approached antitrust with a presumption that the gears of industrial-organization economics and antitrust law meshed more or less synchronously. But such a presumption was unwarranted, to say the least. As the course developed, it increasingly dawned that antitrust law, supposedly devoted to enhancing competition, was more a part of the problem than the solution. A few who had thought about all this longer had figured it out already. But for a callow law student at the time, it was difficult to mesh the economics of competition with "competition" law. I went into the exam conflicted, and evidently it showed. The conflicts today are fewer, thanks to a new brand of antitrust thinking that has developed and a new breed of antitrust enforcers that have arrived over the past generation. Often the new thinkers and enforcers are one and the same. The assistant professor who taught me antitrust is now the Chairman of the Federal Trade Commission, having written prolifically on both the Commission and antitrust law generally. Likewise, seminal scholars - also among my contemporaries and teaching colleagues - such as Frank Easterbrook, Richard Posner and Diane Wood - now as judges apply the new law that they espoused as academics. This article describes aspects of the evolution by which new antitrust rules have emerged to stimulate the salutary (if incomplete) rapprochement between economics and law in antitrust. In effect, the new rules have emerged from various types of competition, of two general sorts. To invoke Harold Demsetz's useful distinction, the competition has occurred in the field and for the field of antitrust. That is, the current generation has witnessed competition, first, as to which intellectual (including economic) paradigm animates antitrust law - competition for the field. As Section I details, competition for the field has included competition in the federal judiciary, some of that competition represented by acts of seeming judicial disobedience in antitrust. Thereafter, there has been considerable competition in the field, along lines to be described in section II, focusing on developments (some desirable, some not) in enforcement of the antitrust laws
