Abstract: This chapter examines the American Civil Liberties Union’s turn away from its defense of mass picketing, strikes, and political dissent, and its antipathy for courts, and toward the modern constitutional ideas of civil liberties for which it is now known. During the period, many of the ACLU’s leading lawyers were Jewish. To many of them, the best bulwark against totalitarianism in America was to prohibit state-sanctioned orthodoxy, whether religious or ideological, even if the target of state suppression was hateful or dangerous speech. This chapter considers the influence of ACLU lawyers’ identity and concerns about antisemitism on the organization’s strategies and goals. It surveys the usual methodological approaches to this kind of question and finds them incomplete—at least as applied to the influence of two lawyers in particular, Arthur Garfield Hays and Morris Ernst, on the ACLU’s evolution. The chapter focuses on the vigorous debate, within early twentieth-century Jewish communities, concerning group rights and individual identity; Jewish identification; and national belonging. Civil liberties, it argues, was a “badge of belonging” for Jewish lawyers navigating a world of labor collectivism, New Deal bureaucracy, civil rights activism, and above all else, a world that seemed to be slipping into illiberal antisemitism, particularly in Europe. Civil liberties were in fact a way of navigating the cross-currents of the world of the 1930s, which oddly enough, might bear a family resemblance to our own—a question that the author foregrounds through the story of her own experience as a public voice on matters of civil liberties and racial prejudice.