After the US Supreme Court curtailed the powers of federal agencies in two cases last week, progressive critics predictably complained that the decisions favored “big business,” “corporate interests” and “the wealthy and powerful.” That gloss overlooked the reality that people with little wealth or power frequently are forced to contend with overweening bureaucrats who invent their own authority and play by their own rules. In the more consequential case, the court repudiated the Chevron doctrine, which required that judges defer to a federal agency’s “permissible” interpretation of an “ambiguous” statute. The majority said that rule, which the court established in...