For more than 30 years, the Environmental Protection Agency has made tenacious efforts to define all aspects of “solid waste,” and it shows no sign of abating. The latest attempt to define this important regulatory term was only partially successful. The U.S. Court of Appeals for the District of Columbia issued another ruling on the EPA’s ongoing project to define the term “solid waste” in the context of regulating the recycling of “hazardous secondary materials.” The author of this article discusses the EPA’s efforts and the court’s decision.