This paper summarizes recent empirical research on compliance costs and strategies and on permit market performance under the U.S. acid rain program, the first large-scale, long-term program to use tradeable emissions permits to control pollution. An efficient market for emissions permits developed in a few years, and this program more than achieved its early goals on time, and it cost less than had been projected. Because of expectation errors, however, investment was excessive, and permit prices substantially understate abatement costs. The tradeable permits approach has worked well, but it is not a miracle cure for environmental problems. Coauthors are Paul L. Joskow, A. Denny Ellerman, Juan Pablo Montero, and Elizabeth M. Bailey. Copyright 1998 by American Economic Association.

Copyright American Economic Association