Partner Series
What Is Sodomy?
Credit: Shutterstock: Andrey Burmakin

Perhaps surprisingly, there is no universal definition for sodomy, at least in the eyes of U.S. law. Just what constitutes sodomy differs between jurisdictions and states.

In three states — Oklahoma, Kansas and Texas — laws against sodomy specifically refer to sexual activity between two members of the same sex. Kansas' anti-sodomy law also prohibits sex with animals, and Montana's now-repealed anti-sodomy law targeted both same-sex sexual activity and bestiality.

But sodomy most often refers to anal or oral intercourse, regardless of the individuals' sex. For instance, Utah's penal code defines sodomy as "involving the genitals of one person and mouth or anus of another person, regardless of the sex of either participant."

Other states also adopt this definition, but use the vague term "crimes against nature," which often includes bestiality. In some cases, sodomy falls under another fuzzy phrase, "deviant sexual intercourse."

In California law, sodomy refers specifically to anal sex, between both same-sex and opposite-sex couples. (Today, the state only criminalizes such acts if they are forced or involve minor children.)

Sodomy laws were originally put in place as an attempt to prevent non-procreative sexual acts, particularly those occurring outside of marriage, according to the American Civil Liberties Union.  In the 2003 landmark case Lawrence v. Texas, the U.S. Supreme Court found Texas' anti-sodomy law unconstitutional, a decision that also invalidated the anti-sodomy laws of other states.

However, at least a dozen states — including Texas — still have anti-sodomy laws on the books.

Last month, Louisiana's House of Representatives voted to reject legislation that would have removed the state's sodomy ban.

Other states are taking steps in the opposite direction. In 2013, Virginia's 4th U.S. Circuit Court of Appeals overturned the state's anti-sodomy law, and Montana Gov. Steve Bullock signed a bill into law that would formally decriminalize sodomy in that state.

Follow Joseph Castro on Twitter. Follow us @livescience, Facebook & Google+. Originally published on Live Science.