Steven C. Salop writes that the Biden administration oversaw a paradigm shift in antitrust, but it was the full adoption of the ideas of the Post-Chicago school, whose intellectual influence has countered Chicago since the 1980s, rather than the empowerment of the Anti-Monopoly or Neo-Brandeisian school of thought. This latter school of thought played an important role by motivating increased enforcement and corralling political support, even if it did not lead to cases that could not have be...