[10] Hoar was also an organizer and major force behind the enactment of the Employee Unemployment Benefits Act, served on the Commission to Compile Information & Data, 1917, taught mathematics and engineering, patented a system for aiming large guns by the stars, and authored landmark works on constitutional and patent law.

Under the pseudonym Ralph Milne Farley, Hoar wrote a considerable amount of pulp-magazine science fiction during the period between the world wars, appearing in such publications as Argosy All-Story Weekly and Amazing Stories, as well as occasional essays for The American Mercury, Scientific American, and science fiction fanzines.

His works include The Radio Man and its numerous sequels, chiefly interplanetary and inner-world adventure yarns in the tradition of Edgar Rice Burroughs, with whom he was friends; Hoar also wrote a number of archetypal time-travel-paradox tales, collected in book form as The Omnibus of Time,[11] and "The House of Ecstasy", which has been frequently reprinted since its initial appearance in Weird Tales (April 1938).

[13] Upon relocating to the Midwest, where he worked as a corporate attorney for the firm of Bucyrus-Erie, Hoar joined the Milwaukee Fictioneers, whose members included Stanley G. Weinbaum, Robert Bloch, and Raymond A. Palmer.

When Chicago-based Ziff-Davis Publishing Company bought the ailing Amazing Stories in 1938, Hoar was offered, but declined, the magazine's editorship and recommended Palmer, who held the position through the 1940s.