It was always recognition that one thing that conspicuously distinguishes women from men is that only women become pregnant; and if you subject a woman to disadvantageous treatment on the basis of her pregnant status, which was what was happening to Captain Struck, you would be denying her equal treatment under the law.IntroductionThis chapter invites consideration of Ruth Bader Ginsburg’s 1972 merits brief in Struck v. Secretary of Defense. The brief is little known because the Supreme Court of the United States eventually declined to decide the case. But anyone seeking to understand the origins and nature of Justice Ginsburg’s views on sex discrimination would be well advised to read this brief. So would anyone interested in deepening an appreciation of how the Constitution speaks to gender equality.In her capacity as general counsel for the Women’s Rights Project of the American Civil Liberties Union, Ginsburg filed the Struck brief a little more than a year after the Court decided Reed v. Reed but before the Court began to shape liberty and equality doctrine concerning the regulation of pregnant women in cases such as Roe v. Wade, Frontiero v. Richardson, and Geduldig v. Aiello. Ginsburg wrote the brief on behalf of an Air Force officer, Captain Susan Struck, whose pregnancy – and whose refusal on religious grounds to have an abortion – subjected her to automatic discharge from military service.