Zack De La Rocha made a surprise appearance on stage alongside Rodrigo y Gabriela at a gig in Colorado on Friday (August 20).
The Rage Against The Machine frontman spoke to fans at the show about The Sound Strike campaign, which opposes Arizona's new immigration law SB 1070.
The controversial law allows police to challenge people they suspect of being an illegal immigrant.
In an impassioned speech, De La Rocha called for fans to “stand up for what is right for civil and human rights”.
The Sound Strike campaign has attracted a series of high-profile supporters, including Kanye West, Serj Tankian and Massive Attack.
Rage Against The Machine also played a one-off gig in Los Angeles last month for the cause.
Rage Against The Machine - Live
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