United States federal Indian policy explicitly targeted the Sun Dance for suppression from the late nineteenth century, with the Bureau of Indian Affairs formally prohibiting it and other Indigenous ceremonies as part of a broader assimilationist campaign that also drove children into boarding schools and criminalised a wide range of Native American religious practice, a documented history of religious persecution that continued in various forms into the twentieth century even as many nations kept the ceremony alive in secret or in reduced and adapted form despite the ban.
The American Indian Religious Freedom Act of 1978, and its 1994 amendments extending specific protections to traditional religious use of otherwise controlled substances, marked a major legal turning point in the United States, formally affirming Native American religious practice, including ceremonies like the Sun Dance, as protected rather than prohibited, though tribal nations and scholars of Native American law have noted that legal protection did not by itself repair the deep intergenerational disruption the earlier suppression caused. The ceremony today is practised openly again among the nations that hold it, generally on reservation land or other tribally controlled sites and, consistent with its closed status, typically not open to uninvited outside observers, a continuation of a ceremony that survived a documented and sustained campaign to end it rather than a simple, unbroken tradition unaffected by that history.
Sources Documents of United States Indian PolicyFrancis Paul Prucha (ed.) with American Indian Religious Freedom Act Amendments of 1994 (Pub. L. 103-344)United States Congress