May’s research and writing has focused on American political and diplomatic history since 1945. Specifically, he has examined the extra-legal methods used by government agencies and their impact on individuals and American civil liberties generally. His recent work on the Voting Rights Act is both a history of how the Act originated, its impact on American democracy, and a case for its preservation as an instrument to fight modern voter suppression movements. As for civic and professional activities, he worked with the Public Citizen Litigation Group in 1985 to force the government to declassify secret grand jury records pertaining to the 1950 indictment of William Remington for perjury (federal grand jury records are sealed in perpetuity unless a federal judge orders them opened, and none had ever been unsealed for “historical purposes”). May put aside his research for the next fifteen months to work with lawyers on preparing a petition (actually several volumes of historical and legal memoranda) which was submitted to the U.S. District court for the Second Circuit in New York. After a lengthy court struggle, U.S. District Court Judge Whitman Knapp sided with the group and ordered that the records be unsealed, which established a precedent that later historians would use to win access to the grand jury records in the Alger Hiss and Harry Dexter White cases and, in 2008, the case of Julius and Ethel Rosenberg. May considers his role in this case to be one of his proudest achievements.