On May 2, 1994, the U.S. Supreme Court joined -- but certainly did not end -- a debate about the disposal of ash produced from burning municipal solid waste in waste-to-energy (WTE) incinerators. In City of Chicago v. Environmental Defense Fund,¹ the Court decided that such ash is not automatically exempt from classification as hazardous waste under the Resource Conservation and Recovery Act (RCRA).² As a result, incinerator operators are responsible for testing their ash and, if it contains hazardous substances at levels in excess of those prescribed by the U.S. Environmental Protection Agency's (EPA's) test for "the characteristic of toxicity," for handling it as hazardous waste.

This Dialogue first provides background on the emergence of WTE incinerators and the controversy surrounding ash from such facilities. It next reviews City of Chicago and, finally, puts the case into perspective by identifying some of its probable consequences, including effects on the incinerator industry, on disposal of municipal solid waste, and on municipalities.