BILLBOARD LIBERATION FRONT. Twenty Years of Billboard Alterations and LiberationsSan Francisco: Masters of Pretzels, n.d. [ca. 1999]. 1 p.; 82 x 53.5; ill. Multiple inks on thick white stock. Numbered and signed by the artist (23/50)

This poster commemorates the 20th anniversary of the Billboard Liberation Front, which coincides with retrospectives held in San Francisco (The Lab, 12 March to 1 April 1999) and New York (CBGB, 28 April to 21 May 1999) .

The Billboard Liberation Front (BLF) was a Situationist-influenced group formed in December 1977 by Jack Napier (John Law) and Irving Glikk. The two men practiced cultural jamming by altering billboards around San Francisco and other major U.S. cities, changing key words to radically alter the message and make it anti-corporate. This detournement-like practice continued for the next several decades. In 2013, Complex Magazine named the BLF #27 of The 50 Most Influential Street Artists of All Time. The BLF maintains an active website documenting its history and current practices at

Founder John Law will be the subject of a major retrospective at the ProArts Gallery and Commons in Oakland, CA this summer. See