John W. Mayo and his co-authors examine how judicial standards in U.S. merger trials have evolved over time. They challenge the view that courts have become increasingly lenient due to the influence of the Chicago School. Using a new theoretical framework and empirical analysis of over 77,000 mergers reported between 1982 and 2021, the authors find that judicial standards have actually become more stringent, with a decline in litigated cases and an increase in antitrust agency success rates.