Measuring voting power in an international institution: the United States and the inter-American development bank

This paper applies a measure of relative voting power to the weighted voting system of the Inter-American Development Bank (IADB). Almost all assessments of internal governance of the IADB and other international financial institutions make reference to members' votes as a proxy for relative influence. But as this paper demonstrates, voting weights are misleading. The number of votes a country has in a weighted voting system does not necessarily denote its ability to affect outcomes. The conventional wisdom holds that the United States is omnipotent in the IADB because it has a large number (over 30 percent) of all the votes. This paper reveals that the U.S. obtains much more control over outcomes than originally intended by the institutions' designers. Received: September 2000 / Accepted: October 2001