In 2019, the HAF along with the American Civil Liberties Union and various Jewish religious and civil rights organizations filed a friend-of-the-court brief with the United States Supreme Court in support of a constitutional challenge to a government-sponsored 40-foot cross as a war memorial in Bladensburg, Maryland in the "American Legion v. American Humanist Association" case. HAF also joined a coalition of interfaith and civil rights groups opposing Project Blitz, a coordinated national effort to enshrine Christian nationalism in state laws in the United States, which could undermine civil rights protections and healthcare access for women, LGBTQ people, those of minority faiths, and the nonreligious. On 12 May 2019, HAF along with the AJC, the U.S. Conference of Catholic Bishops, and other interfaith groups held a solidarity vigil for the 2019 Easter Sunday terrorist bombings in Sri Lanka.