* "Zion in the Courts: Early Mormon Legal History" (1985): This book explores the legal struggles of early Mormons, focusing on their interactions with the American legal system and the challenges they faced.
* "The Book of Mormon and the Law: A Study in the Legal History of the Church of Jesus Christ of Latter-day Saints" (1987): This work examines the legal aspects of the Book of Mormon, including its historical context, its influence on legal practices, and its interpretation within the Mormon community.
* "The Mormon Sister Wives: A Legal and Historical Analysis" (1994): This book delves into the legal and historical complexities of polygamy within the Mormon community, focusing on the controversial practice of plural marriage.
* "An Introduction to Mormon Legal History" (1999): This book provides an overview of the legal history of the Church of Jesus Christ of Latter-day Saints, covering various themes like religious freedom, property rights, and the evolution of Mormon legal thought.
* "The Saints in Missouri: A Legal History" (2000): This book focuses on the legal challenges faced by Mormons in Missouri, exploring the historical context, the legal battles, and the impact on the community.
In addition to these books, Firmage has published numerous articles and essays on Mormon history, law, and culture. His work has been widely cited and is considered an important contribution to the understanding of Mormon legal history.