As an emerging young poet in the mid-1960s, Sinclair took on the role of manager for the Detroit rock band MC5. The band's politically charged music and its Yippie core audience dovetailed with Sinclair's own radical development. In 1968, while still working with the band, he conspicuously served as a founding member of the White Panther Party, a militantly anti-racist socialist group and counterpart of the Black Panther Party. Arrested for distribution of marijuana in 1969, Sinclair was given ten years in prison. The sentence was criticized by many as unduly harsh, and it galvanized a noisy protest movement led by prominent figures of the 1960s counterculture. He was freed on March 9, 1972, by the Michigan Supreme Court when the possession of marijuana law was declared unconstitutional.