Theodore was earlier a member of The Mars Volta, while de la Rocha was a member of Rage Against the Machine. One Day as a Lion is notable for sometimes featuring de la Rocha's melodic singing rather than the rapping style he used with Rage Against the Machine. However, de la Rocha's lyrics continue to emphasize political and activist themes.
On July 16, 2008, the song "Wild International" was available to stream on the band's MySpace page, and was premièred by Australian radio station Triple J. Some sources claimed that Los Angeles radio station KROQ premiered it, but due to international time differences, Triple J actually got the first play.[2] The band's eponymous debut EP was released on July 18th, 2008 in Australia and four days later in the US, and was also released on iTunes.
As of mid-2008, One Day as a Lion is not expected to tour or record a full-length, as de la Rocha is preoccupied with the Rage Against the Machine reunion tour.