For nearly two thousand years, the Western tradition has viewed polygamy as inherently wrong, a crime akin to adultery, prostitution, and sex with minors. Polygamy was a capital crime in the West from the ninth to the nineteenth centuries, and every state in America and every nation in the West still counts it a crime today.

These bans are now being challenged as a violation of the rights of liberty, equality, privacy, sexual autonomy, and (for some) religious freedom. Indeed, Professor John Witte, Jr. contends that polygamy laws will likely become the next hot legal topic on the contested borderlines between constitutional law, family law, and religious freedom. The Jonas Robitscher Professor of Law, Alonzo L. McDonald Distinguished Professor, and director of the Center for the Study of Law and Religion at Emory, Witte is one of the world’s leading scholars of law and religion in Western history. In a comprehensive new 600-page tome, The Western Historical Case for Monogamy over Polygamy (Cambridge University Press, forthcoming 2015), Witte analyzes the history of monogamy versus polygamy in the West from ancient Greek, Roman, and Hebrew sources to the present day, and uses that history to assay the current cultural and constitutional debates about whether polygamy should be criminalized, tolerated, or made a valid marital option along-side traditional and same-sex marriage.

Though criminal, polygamy is currently being practiced, albeit usually discretely, by various Fundamentalist Mormons, Muslim and Hmong immigrants, Native American Indians, and others. Also, mainstream media have begun shining light on the practice. “Popular shows, such as Sister Wives and Big Love, and popular magazines, such as People and Time, are making the polygamous lifestyle look mainstream, even edgy and glamorous,” says Witte.

The hard question is whether these criminal laws against polygamy can withstand a challenge that they violate an individual’s constitutional rights to privacy and sexual liberty, to marriage and domestic autonomy, to equal protection and nondiscrimination, and to religious freedom. Cases challenging polygamy bans have already been filed in Canada and the United Kingdom. And in 2013, a US District Court struck down parts of Utah’s anti-polygamy law in Brown v. Buhman, a case involving the aforementioned Sister Wives family.

“Is polygamy just another one of those stubborn traditional Christian sex crimes inevitably vulnerable to the same constitutional logic of privacy and sexual liberty that toppled traditional laws against abortion, or contraception, or sodomy?” Witte wondered at the 2013 Cary and Ann Maguire Lecture delivered at The John W. Kluge Center at The Library of Congress. “Are defenders of anti-polygamy laws just prudish patriarchs, chauvinists, and homophobes, clutching to their traditional morality at the cost of true liberty for all?”

And could it go even further? If polygamy becomes decriminalized, could it then become legalized?

“With so much marital pluralism and private ordering already available, why not add a further option, that of polygamous marriage?” Witte asks in his new book. “Why not give the polygamist families the same status afforded to other domestic unions recognized by state law? Would that not be better than consigning polygamists to a shadow marriage world controlled by religious authorities who have none of the due process constraints imposed upon state authorities?”

The historical arguments against polygamy have been myriad, Witte notes, and his work reflects the most persistent and common argument—that polygamy is too often the cause or consequence of harm. Both ancient and modern writers have argued it is inherently unnatural, unfair, and unjust to wives and children. In his upcoming book, Witte also demonstrates how polygamy is harmful to men.

The Western Historical Case for Monogamy over Polygamy is the 28th book for Witte, a prolific author who has also published 220 articles and 15 journal symposia.

“Two generations ago, contraception, abortion, and women’s rights were the hot topics,” he says. “This past generation, children’s rights and same-sex unions have dominated the cultural and constitutional wars. On the frontier are hard questions about extending the forms of valid marriage to include polygamy, and extending the forums of marital governance to include religious and cultural legal systems that countenance polygamy. This book aims to put those looming questions in larger and longer context. No such comprehensive historical account exists, and I hope this book will help resource the debates both in the West and well beyond.”

This story appears in the Fall 2014 issue of Emory Law Insights and can be read online, with an accompanying excerpt from The Western Historical Case for Monogamy over Polygamy (Cambridge University Press, forthcoming 2015).