A recent decision by the U.S. District Court for the District of Columbia dismissed a lawsuit brought by Friends of the Earth seeking to compel the Environmental Protection Agency to determine that lead emissions from aircraft using 100LL fuel pose a danger to public health as defined by the Clean Air Act of 1970. The lawsuit effectively halted the development and testing of 100LL alternatives, which is a priority for the general aviation industry. The court dismissed the case on jurisdictional grounds, finding that the EPA’s denial of a citizen’s petition for rulemaking is properly reviewed by the Court of Appeals. Although groups such as EAA and AOPA have long advocated for the development of alternative lead-free fuels for general aviation aircraft without EPA rulemaking or litigation, no lead-free alternative has been certificated for use in general aviation aircraft to date. Accordingly, the Friends of the Earth case might not be the final lawsuit filed on this issue.