Customs union theory and the nonuniformity of tariffs

Allowance is made for the initial nonuniformity of the tariffs of a union country before it joins a customs union. The reduction of such nonuniformity is a possible source of welfare again distinct from the usual trade creation and trade diversion effects. A net welfare gain from a union may result even when the country's total trade stays unchanged and even when all trade with the outsider ceases. A three-product, small-country model is used, domestic production and consumption substitution between the two importables yielding the import pattern effect that produces the possible gains referred to.