Ewbank was born in Guilford, Indiana. He is a descendant of the early Indiana pioneer, John Ewbank, an immigrant from England who settled in Dearborn County in 1811. Louis Ewbank's parents were John William "Will" Ewbank, who worked for the local railroad company, and Betsy Ewbank (née Blasdel).Minde C. Browning, Richard Humphrey, and Bruce Kleinschmidt, "Biographical Sketches of Indiana Supreme Court Justices", Indiana Law Review, Vol. 30, No. 1 (1997), section reproduced in Indiana Courts Justice Biographies page.
