The Chicago-based Oil-Dri Corporation, which, as the maker of Cat’s Pride, is the world’s largest kitty litter company, wants to dig an open-pit clay mine on public land outside of Reno, Nev. But county commissioners have effectively thwarted that plan by refusing to issue a permit to operate a processing plant for the cat litter on nearby private property. The controversy has drawn national attention to Western mining issues, because it hinges on the 1872 Mining Law, which allows miners to extract resources from federal lands without paying royalties to taxpayers. The law makes it virtually impossible for any actor — including the federal government — to deny miners the right to dig. The Nevada case over mining dirt for kitty litter could represent the first time in history that a local government has successfully blocked a proposed mine, and it could set a precedent for getting around the law.