Justice Austin is Diné (Navajo) from northeastern Arizona. While serving on the Navajo Nation Supreme Court from 1985 to 2001, Justice Austin and his colleagues on the Court took the lead on using American Indian customary law in tribal court decisionmaking and in tribal government operations. Justice Austin wrote several Navajo Nation Supreme Court decisions that helped establish frameworks for incorporating Navajo common law into Navajo jurisprudence. Justice Austin was the Herman Phleger Distinguished Visiting Professor of Law at the Stanford Law School in the spring semester of 1995. He has also taught short courses at the Harvard Law School, Arizona State University College of Law, University of Utah College of Law, and in Italy and Spain. Justice Austin also served as a judge pro tempore on the Arizona Court of Appeals, Division I (1993-1994).

Justice Austin's book, Navajo Courts and Navajo Common Law, A Tradition of Tribal Self-Governance (University of Minnesota Press, 2009), is the only book available on the Navajo Nation Courts and Navajo Common law. Justice Austin's other writings include: The Twenty-Fifth Anniversary of the Navajo Preference in Employment Act: A Quarter-Century of Evolution, Interpretation, and Application of the Navajo Nation's Employment Preference Laws, 40 New Mexico Law Review 17 (Winter 2010) (with co-author Howard Brown), and American Indian Customary Law in the Modern Courts of American Indian Nations, 11 Wyoming Law Review 351 (2011). Justice Austin teaches Tribal Courts Clinic in the fall semester and Tribal Courts and Tribal Law in the spring semester.