The most recent issue of The Hastings Center Report has a very interesting article on emergency contraception, so-called Plan B. The author, Rebecca Stangl, argues that even if opponents of Plan B are right that emergency contraception works, at least sometimes, by making the uterus inhospitable to a fertilized egg, it does not follow that there is no moral difference between Plan B and abortion. Her analysis of the case in relation to the principle of double effect is worth reading. Registration is required, by registered users can read the article here.