12/02/2013 11:18 am ET Updated Feb 01, 2014

The Supreme Court Should Adhere to Scientific Definitions When Hearing Anti-Contraception Lawsuits

Last week, the Supreme Court granted certiorari in two cases, Sebelius v. Hobby Lobby Stores and Conestoga Wood Specialties v. Sebelius. These cases, along with more than 80 others, challenge a provision of the Affordable Care Act that guarantees no-cost coverage of preventive services, including all FDA-approved contraceptive drugs and devices.

There are a number of important issues at play in these cases, but a central one should be this: must the law accommodate those whose religious beliefs lead to conclusions that are scientifically incorrect?

The plaintiffs in Hobby Lobby and Conestoga do not object to covering contraception per se. Instead, they object to covering emergency contraceptive pills and intrauterine devices because they believe those items cause abortion.

Their assertions, however, concern matters of science rather than faith and, as such, must be supported by verifiable evidence. And an examination of their claims shows that they get the science wrong in two critical ways.

First, they mischaracterize any drug or device that interferes with the implantation of a fertilized egg as an abortifacient. Second, they incorrectly claim that emergency contraceptive pills such as Plan B One-Step® and ella® prevent the implantation of a fertilized egg.

Let us consider each in turn.

First, as a number of esteemed scientists and medical groups attested in a friend-of-the-court brief submitted to the Supreme Court in the Hobby Lobby matter, "Abortificient has a precise meaning in the medical and scientific community and it refers to the termination of a pregnancy. Contraceptives that prevent fertilization from occurring, or even prevent implantation, are simply not abortifacients regardless of an individual's personal or religious beliefs or mores."

Contrary to popular belief, pregnancy does not occur in a "moment" of conception within hours of intercourse, but rather over a span of several days. Intercourse can result in the fertilization of an egg any time between five days before and one day after ovulation, when the egg is released from the ovary. Once the sperm fertilizes the egg, the embryo travels to the uterus, where the cells begin to divide, forming a blastocyst. The blastocyst then begins to implant itself in the uterine lining. Some embryos begin this process but never complete it. Pregnancy is established only when an embryo successfully attaches to the uterine wall, approximately 5-9 days after fertilization.

What this means is that an embryo can be present in a woman's body for up to 9 days before she becomes pregnant. Most forms of routine and emergency contraception prevent fertilization by keeping the egg and sperm from meeting. But even methods that may interfere with implantation act before a woman has become pregnant. And it should go without saying that a woman must be pregnant before she can have an abortion.

Think about all the women who try in vitro fertilization but do not become pregnant (IVF results in pregnancy approximately 37% of the time). With IVF, an egg is fertilized in a petri dish and the embryo is then transferred to the uterus. That act alone does not make a woman automatically pregnant. If the embryo does not attach, she simply never became pregnant. The same occurs all the time with eggs that are fertilized following intercourse. Indeed, approximately half of all eggs that are fertilized naturally fail to implant.

Second, even by the plaintiffs' own inaccurate definition of pregnancy, emergency contraceptive pills fail to qualify as abortifacients because they have no impact on implantation. While opponents of emergency contraception are quick to cite the Plan B label, which says it may inhibit implantation, that label has not been updated since the drug was first approved in the U.S. in 1999 and is now very much out of date. Current research shows that it works by delaying or preventing ovulation. Indeed, the makers of the European equivalent of Plan B One-Step®, Norlevo®, just updated their label to say that the drug "cannot stop a fertilized egg from attaching to the womb." Similarly, all the evidence available indicates that ella®, like Plan B One-Step®, is ineffective at preventing pregnancy after ovulation has occurred.

It is important for each woman to understand how a given contraceptive method works so that she can decide for herself whether using it comports with her own moral code. But it is not her boss's place to take away that decision from her by excluding contraceptive options from her health plan. And it is not the government's obligation to accommodate an employer's redefinition of well-established medical categories, even when premised on sincerely-held religious beliefs.

The CEOs who want to deny birth control coverage to their employees are entitled to their own religious beliefs, but not to their own facts. And they certainly are not entitled to impose fact-free beliefs on their employees.