Last month on Trade Diversion:

A new discussion paper by Antoni Estevadeordal, Caroline Freund, and Emanuel Ornelas says that regional trade deals amongst Latin American countries have been building blocks for multilateral liberalization — “there is strong evidence that preferences induce a faster decline in external tariffs in free trade areas“.

This contrasts with Nuno Limão’s results for the United States and Europe, where “multilateral tariff reductions in PTA goods were smaller than those in similar goods not imported from PTA partners.”

Last week’s Economist:

In fact, the evidence is mixed. One study argues that America cut multilateral tariffs more slowly on goods to which it had extended preferential access. A new analysis reaches the opposite conclusion for Latin America. The history of the past two decades suggests the two can coexist. Multilateralism has hardly been moribund as regional deals have mushroomed. The Uruguay round of global trade talks ended, the WTO came into being and the Doha round began.

You read it here (with citations!) first.