On 'CU can dominate UTR'

For a decade and a half, Cooper and Massell's (1965) conclusion that a poli cy of unilateral tariff reduction (UTR) is superior to the formation of a c ustoms union (CU) remained unchallenged. However Wonnacott and Wonnacott (1 981) using a more realistic model, claimed to show that UTR need not domina te a CU. Here, we point out that the Wonnacott and Wonnacott model is incom plete since their CU does not have a common external tariff, and demonstrat e that the incorporation of such a tariff in their analysis restores the va lidity of the Cooper and Massell proposition.