There are multiple artists with this name: 1) John Sinclair (born October 2, 1941 in Flint, Michigan, United States) is a Detroit poet, one-time manager of the band MC5, and leader of the White Panther Party from November 1968 to July 1969. He was jailed in 1969 after giving two joints of marijuana to an undercover narcotics officer. His case received international attention when John Lennon performed at a benefit concert on his behalf in 1971.
