This week's Supreme Court ruling that the Affordable Care Act violated the craft store chain Hobby Lobby's religious freedom by requiring it to provide employees with insurance coverage for certain contraceptives was based on a complete misunderstanding of how these forms of birth control work. The owners of Hobby Lobby believe the contraceptives—Plan B, Ella and intrauterine devices (IUD)—cause abortions, which they object to as Christians. It is scientifically accepted that pregnancy starts when a fertilized egg implants in the uterus. These contraceptives, however, act before implantation so they cannot be said to terminate pregnancy.



Yet some religious practitioners, including the owners of Hobby Lobby, hold that life begins at conception—when the sperm fertilizes the egg. They believe that these particular contraceptives interfere with the fertilized egg, which they view as destruction of life. Scientific studies indicate this isn’t the case either. Rather, these contraceptives appear to work before fertilization. For instance, Plan B affects ovulation, thereby ensuring that the egg never meets a sperm. This hormonal contraceptive operates similarly to other birth control pills. “We have a very high level of certainty that Plan B only works before ovulation,” says Kelly Cleland, a population researcher at Princeton University.



Medical experts understand less clearly how the other methods of contraception act, because all of them have multiple effects on the egg, sperm and uterus. They can impede sperm mobility, change cervical mucus and modify uterine lining as well as slow the movement of an egg or prevent its release. Although researchers allow that IUDs could potentially interfere with implantation of a fertilized egg, studies indicate that the devices mainly impede pregnancy prefertilization. “With the IUD, the primary mechanism impacts ovulation and sperm behavior,” says Jeanne Conry, past president of the American Congress of Obstetricians and Gynecologists (ACOG).



But again, as Cleland and Conry emphasize, preventing implantation of a fertilized egg isn’t abortion. Another form of emergency contraception—Ella—only recently became available, so researchers have yet to study its modes of action as extensively as those of other methods. But Ella “is just a variation on the theme for the IUD,” Conry explains.



It’s unclear why the known medical science behind these contraceptives did not seem to bear on the Supreme Court’s decision. In the case of Plan B, it’s evident that the contraceptive does not violate Hobby Lobby’s religious beliefs about abortion. Research also suggests that the other contraceptives don’t conflict with such religious beliefs either. This means that, at least in part, Hobby Lobby based its argument on scientific ignorance. Medical organizations such as the ACOG conveyed the science during the trial, but to no avail—at least for the justices rendering the majority opinion. “We made these points every step of the way,” Conry says, “but the Supreme Court decided on religion, not science.”