O'Hara served as an attorney for various villages, cities, towns, and school districts, as well as county attorney of McLeod County (1934 – 1938).
oʊhˈɑːɹɹə sˈɜːvd æz ɐn ɐtˈɜːni fɔːɹ vˈɛɹiəs vˈɪlɪdʒᵻz, sˈɪɾiz, tˈaʊnz, ænd skˈuːl dˈɪstɹɪkts, æz wˈɛl æz kˈaʊnti ɐtˈɜːni ʌv mək lˈaʊd kˈaʊnti nˈaɪntiːnhˈʌndɹɪd θˈɜːɾi fˈoːɹ nˈaɪntiːnhˈʌndɹɪd θˈɜːɾi ˈeɪt.