Is Incest Next?

37 Pages Posted: 29 Sep 2003

See all articles by Brett McDonnell

Brett McDonnell

University of Minnesota Law School


This paper examines how the Supreme Court's decision in Lawrence v. Texas (the gay sodomy case) affects laws regulating other forms of sexual behavior, focusing in particular on consensual adult incest. It engages in and compares two kinds of inquiries: formalist and realist. The formalist inquiry attempts to make sense of Lawrence using traditional legal materials. One must identify the implicated individual liberty interest and examine the extent to which the interest is constitutionally protected. The paper identifies three basic approaches to identifying liberty interests, all with some support in the Court's history. The "conservative Burkean" approach recognizes a right only if it can be clearly shown that the our society has specifically and widely acknowledged the right for a long time. The "Millian" approach forbids the state from regulating behavior which directly affects only those who engage in it and does not harm anyone else. The "liberal Burkean" approach looks to our history and is unwilling to impose a simple general harm principle, but is willing to allow that over time we may come to recognize new sorts of interests that should be protected. The paper argues that the Court has taken a Goldilocks position: conservative Burkeanism is too restrictive, Millianism is too expansive, and liberal Burkeanism is just right. After identifying the liberty interest, one must identify the state's interests in regulating that behavior. Lawrence is ambiguous as to what level of scrutiny applies to the government's asserted interests. The formalist analysis ends by comparing the individual liberty interest with the asserted state interests. Several interests might justify laws against consensual adult incest, including the risk of genetic defects, protecting relations within the family from becoming overly-sexualized, and reinforcing moral norms. All of these justifications have problems, though. The formalist analysis is indeterminate, but suggests that core forms of incest are probably constitutional, although laws against incest between cousins and perhaps against incest between step-relatives may be more vulnerable to judicial review.

The realist inquiry views the Court as a political institution and asks how it is likely to respond to future cases given both the preferences of its members and the political constraints which they face. This inquiry suggests that the Court is less likely to strike down incest laws than sodomy laws, both because there is no major political group attempting to repeal incest laws and because general social norms against incest have weakened less than those against sodomy, although that may be less true for non-core forms of incest such as incest between cousins. The realist inquiry thus also suggests that the Court would not strike down the core incest laws, and this conclusion seems firmer than the formalist analysis. If the Court ever does protect incest, it will happen only when most Americans are unwilling to throw people in jail for that behavior.

Keywords: Lawrence, incest, sodomy, liberty, substantive due process, formalism, realism

JEL Classification: K10, K42

Suggested Citation

McDonnell, Brett H., Is Incest Next?. Available at SSRN: or

Brett H. McDonnell (Contact Author)

University of Minnesota Law School ( email )

229 19th Avenue South
Minneapolis, MN 55455
United States
612-625-1373 (Phone)

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