Sadly, little of Maurice Hauriou's work has been published in English.
These are the only references that I am aware of:
Maurice Hauriou, Tradition in Social Science, Amsterdam/New York, NY, 2011, XXVII, 303 pp. Translation from French with an Introduction by Christopher Berry Gray. Hb: 978-90-420-3419-8
Joseph Broderick, The French Institutionalists: Maurice Hauriou, Georges Renard, Joseph T. Delos, Harvard University Press, Cambridge, Massachussets, 1970, xxv-370p. Extracts from the writings of Hauriou, Renard and Delos.