The Chicago School of antitrust theory, which Richard Posner represents, is an improvement over the old-line neoclassical school. But he still believes that judges can know better than markets how property rights should be assigned.
See Walter Block’s important critique in this .pdf file from the Review of Austrian Economics: “Total Repeal of Antitrust Legislation: A Critique of Bork, Brozen, and Posner”.
Also see Dominick Armentano’s “Antitrust Reform: Predatory Practices and the Competitive Process”
Purchase the definitive book on Antitrust and the Microsoft case: Antitrust: The Case for Repeal.
For more information, see Mises.org on Microsoft.
