MEIC is perhaps best know for the twice-won, citizen-initiated law banning cyanide heap-leach mining in Montana, which has now been upheld in the district, federal, and state Supreme courts despite Canyon Resources, Inc.’s efforts to repeal it in order to develop a massive open-pit, cyanide leach gold mine less than 800 feet from the Blackfoot River headwaters. 

Initiative 137 was a response to the abysmal track record of open pit cyanide leach mining in Montana, as exemplified by cleanup fiascos  at the Golden Sunlight, Zortman/Landusky, and Kendall mines and the Montana Department of Environmental Quality's failure to adequately regulate such mines as required by state law.