In the seemingly endless climate change debate, the regulation of greenhouse gases (GHGs) is a contentious issue among scientists, advocacy groups, lawmakers and businesses. Opinions are strong and varied as to how GHG emissions affect the environment and to what extent they should be controlled.

In 2004, a group comprising eight states, New York City and three non-profits sued six GHG-emitting electric power corporations–American Electric Power Company, American Electric Power Service Corporation, Cinergy Corporation, Southern Company, Tennessee Valley Authority and XCEL Energy–for allegedly contributing to global warming. The plaintiffs in Connecticut v. American Electric Power claimed the utilities’ carbon dioxide (CO2) emissions were a public nuisance causing an array of environmental and personal injuries, including smog-induced respiratory problems; deaths related to prolonged heat waves; property-damaging floods; a decrease in mountain snowpack, a key water source for California; beach erosion from rising sea levels; and loss of biodiversity.