Members of the band At the Drive-In, Cedric Bixler-Zavala and Omar Rodriguez-Lopez, were in De Facto with audio technician Jeremy Michael Ward. De Facto included Cedric on drums, Omar on bass, and Jeremy with various loop, vocal, sound, and distortion effects - a composite of sounds, hinging squarely on tripped-out, instrumental dub. Though De Facto started as a local band with a rock feel, they were rooted in the realm of dub reggae pioneers such as Lee Perry and Dr. Alimantado. The group also dabbled in electronica, Latin/salsa, and jazz which provided them with a distinct sound. The band played local shows around their home town, El Paso, Texas, and released their first album How do you dub? You Fight for Dub. You plug Dub in. The group eventually moved to Long Beach, California in 2000 and the keyboardist Isaiah "Ikey" Owens was added to the band lineup. In 2001, De Facto released their second album, Megaton Shotblast on Gold Standard Laboratories, and received instant success. They were also members of the group At the Drive-In, which established much of their fan base. De Facto continued experimenting with new sounds after Omar decided to end to his time with At the Drive-In, taking Cedric along with him. The rest of the band went on to form Sparta). Omar cited frustration with growing mainstream success, as well as creative suffocation as his motivation for quitting At the Drive-In. Eva Gardner joined the De Facto, and it became what is now The Mars Volta - a new project they envisioned would fulfill their creative desires. The initial lineup for their first public show at Chain Reaction in Anaheim, California was De Facto plus Eva Gardner and Jon Theodore. Also, during 2001, the band recorded two songs with Alex Newport, becoming their first demo. They recorded three more tracks with Alex Newport, becoming the Tremulant EP, sparsely released in early 2002.

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