b'We consider a monopolistic supplier\\u2019s optimal choice of wholesale tariffs when downstream firms are privately informed about their retail costs. Under discriminatory\\npricing, downstream firms that differ in their ex ante distribution of retail costs are offered different tariffs. Under uniform pricing, the same wholesale tariff is offered to all downstream firms. In contrast to the extant literature on thirddegree price discrimination with nonlinear wholesale tariffs, we find that banning discriminatory wholesale contracts\\u2014the usual legal practice in the EU and US\\u2014 often is beneficial for social welfare. This result is shown to be robust even when the upstream supplier faces competition in the form of fringe supply.'