Do antitrust lawyers drink beer, or for that matter grocery shop? Those questions come to mind after watching the U.S. Justice Department trot out its traditional pseudo-science to block a brewery merger. Last week the government filed an antitrust suit to prevent Budweiser maker Anheuser-Busch InBev from buying the half of Grupo Modelo that it doesn't already own. Based in Mexico, Modelo brews Corona Extra and other brands.

Antitrust law is allegedly to prevent firms from exercising monopoly power to abuse customers. But antitrust...