The second threat to railroad hegemony was legal. Until the passage of the Mineral Leasing Act of 1920, United States law allowed a maximum coal land ownership of 640 acres. This unrealistic amount was regularly exceeded through the use of "dummy" entrymen and the abuse of the state selections process. Federal trust-busting litigation against the Rio Grand consortium in 1906 through 1912 resulted in an out-of-court settlement that confirmed the land titles of the railroad and its subsidiaries, the Pleasant Valley Coal Company and the Utah Fuel Company. Several "independent" (non-railroad affiliated) developers, who had began new coal operations on the assumption that the Book Cliffs railroad-coal monopoly was over, were also indicted. The independents' developments included mines initiated by brothers Arthur and Frederick Sweet, first at Kenilworth (near Castle Gate) and later on the Black Hawk vein in southwestern Carbon County, which proved a developers' magnet from 1910 to 1917. A case involving the latter area still stands as the national precedent for state selection of mineral lands (U.S. v. Sweet, 245 U.S. 563 [1918]).

The richness of the Book Cliffs areas attracted other developers. Mormon businessman "Uncle" Jesse Knight began work in the Spring Canyon district in 1912, where several others followed in the period up through World War I. This burgeoning growth--and later bust--exemplified the third challenge to the Utah coal industry: periodic production cycles triggered by outside economic dislocations. Expansions created by the heightened demands of World War I affected pre-established Book Cliffs areas. Meanwhile, the development of known deposits in Emery County to the south lagged behind because of the lack of railroad transportation.