In the early 1970s, Downey was active in the anti-war movement including the Moratorium to End the War in Vietnam in October 1968 and the demonstration in Washington in May 1970 following the invasion of Cambodia and the shootings at Kent State. That summer, Downey began working for Senator George McGovern on the McGovern-Hatfield amendment to cut off funding for the war in Viet Nam. As a conscientious objector, Downey performed alternate service with Americans for Indian Opportunity, a leading educational group for recognition of Native American civil rights. He worked on the legislation returning Taos Blue Lake to the traditional tribe and on the Indian Education Act. During law school, he worked on the staff of the McGovern-Fraser Commission on revisions to the Democratic Party's presidential nomination process. The committee is largely credited with replacing state conventions and party caucuses with presidential primaries to select delegates to the national convention.