As Court-watchers prepare for tomorrow’s Supreme Court oral arguments in Sebelius vs. Hobby Lobby Stores, one point of contention in the debate surrounding the case is the employer’s claim that its faith-based objection to the Obamacare contraceptive coverage mandate extends only to birth control methods it deems “abortifacients”–i.e., IUDs and “emergency contraception” that arguably prevents implantation of a fertilized ovum in the uterine wall. If there is no actual scientific basis for the belief that pregnancy begins with fertilization rather than implantation, you’d have to assume Hobby Lobby’s argument would be significantly weakened if not demolished.

That’s apparently the assumption made by Lin Fang-Wen, a family doctor who penned a column for TPMCafe arguing that allowing religion-based challenges to the scientific and medical consensus regarding, well, scientific and medical questions would be calamitous.

Pregnancy occurs when a fertilized egg implants into the uterine lining. After implantation, that’s when a pregnancy test turns positive. Even among women not on birth control, not every fertilized egg implants. Therefore, the possibility that the copper IUD could inhibit implantation does not make it an abortifacient. This is not an opinion. This is the shared consensus of the medical and scientific community, including the American College of Obstetricians and Gynecologists….

I do not question the religious beliefs of those who disagree with the contraceptive coverage requirement. However, the media should not report their beliefs as medical facts. Suggesting otherwise or claiming that there is “unsettled science “about how contraception works is false.

Antichoice advocates, of course, are willing and able to trot out an array of scientists and physicians who hold to a minority position that “pregnancy” begins with fertilization rather than implantation, so it’s not clear a court of law would agree that ACOG’s definition is dispositive.

But I also wonder if in the end this is a distinction without a difference, at least in terms of the “religious liberty” argument. Suppose that the owners of Hobby Lobby were traditionalist Catholics holding to the Vatican’s long-standing opposition to any form of “artificial contraception,” or were among the growing number of conservative evangelicals who take the same position. Would their “religious liberty” argument be any weaker? Perhaps courts would assign some weight to the idea that the mandate involved complicity in alleged homicide rather than merely sexual impropriety or defiance of a divine command to limitless fecundity. But that’s not entirely clear.

This entire argument clearly will matter, however, in the court of public opinion, where faith-based objects to abortion–however defined–are better-accepted that similar condemnation of contraception. That’s because the vast, vast majority of women of child-bearing years, whether Protestant, Catholic, liberal or conservative, non-Christian or non-believers, rely on it, and are likely to identify far more with the women denied coverage than with the tender consciences of Hobby Lobby’s proprietors.

Ed Kilgore

Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.