The Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) established the Superfund to expedite cleanup of sites with hazardous contamination of natural resources, while imposing the costs on those responsible. Six years later, the U.S. Department of Interior (DOI) (defendant) promulgated regulations governing damages assessment. Ten states, several environmental organizations, industrial corporations, and an industry group (plaintiffs) promptly challenged the regulations. The states and environmental groups argued that the lesser-of rule would undervalue harm to natural resources, allowing damages insufficient to pay restoration or replacement costs. Meanwhile, the private organizations argued that the rule would encourage excessive damages. Then Congress enacted the Superfund Amendments and Reauthorization Act (SARA), requiring DOI to amend its regulations to conform. The courts consolidated a second lawsuit challenging the amended regulations and proceeded to the Circuit Court.