This is no idle academic spat. English common law provides the basis for much of the legal precedent in the U.S. (and elsewhere in the former British empire.) More importantly, in his majority opinion in Roe v. Wade, Justice Harry Blackmun cited the historic acceptability of abortion. It is “doubtful that abortion was ever firmly established as a common law crime,” he wrote.

Carla Spivack, a scholar of the law and English literature at the Oklahoma City University School of Law, argues that dating back to the 14th century in England, many sources suggest abortion was not considered illegal before the point of “quickening,” or when the woman was able to feel the child move in her womb. This usually occurred at about four months, or 16 weeks of gestation. Even after quickening, abortion was typically judged a misdemeanor at most. Women who wanted to terminate their pregnancies used various herbs and tinctures, and the effects of these potions were well-known among midwives.

Meanwhile, a Villanova University law professor named Joseph Dellapenna claims the truth is just the opposite in almost every way. He says abortion was consistently criminalized in England since roughly 1200. According to him, prosecutions for abortion have been happening for centuries, usually out of concern for the unborn child. He’s laid out his thinking in a book and in several briefs in high-profile Supreme Court cases on abortion.

In a rebuttal to Dellapenna published in the William and Mary Journal of Women and the Law in 2007, Spivack argues that when abortion was prosecuted, it was mainly done as a way of either cracking down on illicit sex or punishing a man who injured a pregnant woman. (Dellapenna says many abortion attempts were, in fact, prosecuted as witchcraft.) Authorities at the time were more concerned about prostitutes and vagrancy than they were abortion, Spivack writes, and the state had little say in what happened between married couples. For example, in the aftermath of one abortion in 1742 in Connecticut, as explained by the historian Cornelia Hughes Dayton, there seemed to be just as much concern over the fornication that took place as there was about the destroyed fetus.

“This is why [Dellapenna] hates me,” Spivack said, perhaps only half-jokingly.

According to Spivack, the Anglo-Saxons, the people who inhabited Great Britain from the 5th century, believed that the soul entered the body during quickening. “The baby moves, and it displays an ability to be animated,” she said. “They thought that was what having a soul meant.”

And of course, medical thinking at the time was a bit more ... imaginative. Bodies were thought to be ruled by humors, and Spivack argues that some miscarriages were considered a normal type of purging, not unlike bleeding. Midwifery manuals from the 17th century speculate that before quickening, it’s impossible to know whether the fetus is even human. “[M]onsters of all sorts [can] be formed in the womb,” wrote one such midwife. In addition to human children, women could also become pregnant with “false Moles,” or non-sentient lumps of flesh and veins. Quickening was the only way to know for sure if you were pregnant—and what with.