Hormonal emergency contraception (EC) is engendering fierce moral disagreement that is bleeding over into politics and policy. This paper considers Catholic positions on this issue, as they are the fullest and best developed. Its most extreme opponents, such as representatives of the Vatican, hold that EC is an abortifacient that should be banned. Moderates like Sulmasy believe that it should be available to women who have been raped when a negative pregnancy test suggests that fertilization has not yet taken place, and liberals, like Catholics for Free Choice, believe that it should be available to all women regardless of its mode of action. These positions depend in part on underlying philosophical presuppositions about when valuable life begins and scientific assumptions about how EC works. I argue that there are good reasons for rejecting the criterion of fertilization, and that the best current evidence strongly suggests that EC has no post-fertilization effects. These points by themselves undermine key objections to EC. I also show that none of the remaining considerations are sufficiently compelling to warrant overriding women's right to exercise religious, moral, and political agency in preventing undesired pregnancies.