On Jan. 28, 2016, the Michigan State Senate passed a bill amending a portion of the state penal code dealing with animal cruelty. The bill, from Republican Sen Rick Jones, cracks down on using, selling, or breeding animals for “fighting and baiting,” but it leaves uncorrected old outdated laws about unnatural sexual acts. According to Michigan law, it is a felony for anyone to “commit the abominable and detestable crime against nature either with mankind or with any animal.” This is language that Sen. Jones did not see fit to strike from the record. The bill doesn’t outlaw sodomy, but the truth is that sodomy is already criminalized in Michigan, even if the laws are never enforced.

Sodomy laws—that is, legislation that prohibit anything but vaginal intercourse between heterosexual married couples—are nothing new. Prior to 1962, sodomy was a felony in every state in the union, punishable by imprisonment, and until 2003’s Lawrence v. Texas 13 states still had sodomy laws on the books. In many of these states sodomy laws included oral sex as well as anal sex. It was only in 1971, for example, that Alaska decriminalized oral sex between a married heterosexual couple.

In other countries, sodomy laws have been explicitly gendered, targeting men rather than women. The Buggery Act of 1533, passed by questionable moral authority Henry VIII, made anal penetration and bestiality crimes punishable by hanging. The law was rather eccentrically applied. Nicholas Udall, the headmaster of Eton College (alma mater of Princes William and Harry) and the first person charged under the law in 1541, for abusing his students, was imprisoned, only to be released and later become head of the equally prestigious Westminster School.

Women have historically fared much better than men. Lesbianism has never been a crime in the U.K. Urban legend attributes this to the idea that Queen Victoria simply could not believe that ladies really did such things. That this is a myth doesn’t blunt the fact that women have had it better, legally speaking. This was true even in the medieval period: In the eighth century Pope Gregory III proscribed penances of 160 days for lesbian offenses and a year for male same-sex relations. Rare exceptions to this rule, in the U.S., include New Haven Colony, which included same-sex acts between women as part of its sodomy laws in the 1600s, and the prosecution of women for engaging in fellatio and cunnilingus in the 1920s.

The implementation of these laws has always favored the wealthy and the white. As William Eskridge shows in his book, Dishonorable Passions, in the 18th century it was immigrants and men of African descent who were vulnerable to accusations and prosecution. In fact the lone capital case of that century involves a slave named Mingo who was executed for “forcible buggery.”

While homophobia looms large here, the intellectual basis for sodomy laws has been that anal sex (whether between men or between a man and a woman) is non-procreative. The impetus for this procreative focus is a religious one based in natural law: The Catholic Church’s opposition to contraception is grounded in the understanding that all sex should be open to life. But non-procreative sex hasn’t always been viewed with disdain by religious groups. Some ancient Near Eastern priestesses, sworn to vows of chastity, practiced anal sex as a means of contraception. In Egyptian mythology, it’s not homosexual anal sex that is the problem but the way it inscribes a certain power dynamic and—in an episode of rape—attempts to seize power. Similarly, in Greek and Roman society, the problem wasn’t male-male relations, it was assuming a passive (and, thus, subordinate) sexual role out of keeping with one’s social status.

What sodomy laws in general and the Michigan Penal Code in particular do is draw upon a storied religious tradition that links all “unnatural” sexual acts together. So relations between consenting male adults are grouped with relations between human beings and animals. Bestiality and homosexuality are natural bedfellows in heteronormative rhetoric. This much is implied in the Book of Leviticus, in which laws stipulating that men who lay with men should be stoned to death are found in close proximity to laws proscribing the death penalty for bestiality.

The New Testament stays silent on the question of homosexuality, but early Christians worried about how difficult it is to regulate human sexual conduct. In legislating sex, the author of the apocryphal second-century Epistle of Barnabas strikes upon an ingenious solution. He interprets the prohibitions against eating certain animals in the Hebrew Bible as warnings against the sexual practices that they represent. So hares are seen as representing child molestation, hyenas stand in for adulterers and perverts, and weasels embody oral sex. What this means in practice is that if you have oral sex you might up giving birth through your mouth (like the weasels).

The rationale for these associations lies in erroneous zoology. The hyenas, we are told, change sex from male to female every year. This isn’t true, of course, but the enlarged clitorides of female hyenas meant that people in the ancient world were often confused about their gender and would see “male” hyenas give birth. Similarly there was a popular ancient misconception that weasels copulated and gave birth through their mouths, probably based in the fact that weasels carried their young around in their mouths.

The message here is clear—if you molest children, are a sexual “pervert,” or engage in oral sex, you’re no better than an animal, and risk undergoing the same physical changes that they do. Adding an orifice annually like the hare or giving birth through one’s mouth like the weasel is socially awkward. The genius of Barnabas’s threat is his ability to threaten those he sees as sexual sinners with public exposure.

While for the Greeks and the Romans anal sex was rarely problematic, Christian morality soon overran the empire and by the medieval period sodomy was generally regarded as a crime punishable by death. By the 13th century, French law stipulated castration for the first homosexual offense, dismemberment for the second, and burning for the third. In the Quran, liwat (homosexuality) was grouped with the crime of adultery, but by the medieval period Islamic scholars disagreed on the appropriate punishment for those found guilty. Only one of the four schools of thinking advocated for the death penalty on the basis that it was a form of adultery. The method of execution was also debated. Some recommended stoning, others burning, and others still the ISIS-favorite, being thrown headlong from a minaret (followed by stoning). In 1858, during a period of secularization and renewed interest in women’s rights, homosexuality was actually decriminalized in the Ottoman Empire.

Today, sodomy laws are all but defunct. In 2003, the Supreme Court struck down Texas’s sodomy laws, and in doing so invalidated similar statutes in 13 other states. Michigan’s sodomy laws are unenforceable. The good news, then, is that these laws are toothless. Unless you give birth through your mouth, in which case legal trouble will be the least of your worries.