Via today's Religion Dispatches, I learn that, even according to the Catholic Bishops' own guidelines for hospitals, the "contraceptives are abortifacents" argument is hollow:
The Catholic bishops were among the earliest promulgators of the conflation of ECPs and abortion. Around the time the first ECPs were approved, new laws were being considered to require insurers to cover prescription contraceptives, which were routinely excluded from health insurance. The Catholic Church was looking for ways to quash the measures based on its moral opposition to non-procreative sex. ...
While studies haven’t been conducted in such a way that can absolutely rule out post-fertilization effects, it’s worth noting that, ironically, Catholic hospitals accept the use of emergency contraception. The Ethical and Religious Directives for Catholic Health Care Services, the bishops’ own guide to what Catholic hospitals can and can’t do, say that a woman who has been raped can be treated with ECPs (with the caveat that there is “no evidence that conception has occurred”). This would be absolutely prohibited if emergency contraception was believed to be an abortifacient.
This will, of course, do nothing to stop the chorus of disinformation from those who are ideologically committed to the contraception mandate in particular, but also to Obamacare in general.