Mirant Mid-Atlantic, LLC v. Montgomery County

An electric utility filed a lawsuit against Montgomery County, Maryland, challenging its tax on local carbon dioxide emitters that effectively applied only to the utility’s coal-fired power plant. In May 2010, the county enacted a law that imposed a $5-per-ton tax on carbon dioxide emissions from stationary sources emitting more than one million tons of carbon dioxide annually. The lawsuit contended that the tax constituted a bill of attainder and that it violated the Fourteenth Amendment’s guarantee of equal protection and the Eighth Amendment’s ban on excessive fines.