Since the United States changed its guidelines in 1984, many industrialized nations have included efficiencies defenses in their rules for judging whether mergers and other activities that might lessen competition are on balance desirable. This paper was written for an OECD competition policy conference in Paris October 25, 2012. It presents the standard Williamson “tradeoff” analysis and explores why consumer price benefits might be required in the current economic environment, with its substantial unemployment and Keynesian liquidity traps that limit the reinvestment of efficiency-based profits in additional output. It also explores the difficulty of assessing efficiency benefits in advance of mergers and suggests alternative approaches to the problem.
Scherer, F.M. "Merger Efficiencies and Competition Policy." HKS Faculty Research Working Paper Series RWP12-048, October 2012.