"The hearing started but ended early because the inmate fell ill and had to leave for treatment," Jeffrey Callison, press secretary of the California Department of Corrections and Rehabilitation, told CNN.
Davis, 69, a follower of notorious cult commune leader Charles Manson, is serving a life sentence for first-degree murder for the 1969 slayings of music teacher Gary Hinman and stuntman Donald "Shorty" Shea.
Davis won parole in 2010, but then-Gov. Arnold Schwarzenegger overturned it.
The hearing was being held at the California Men's Colony in San Luis Obispo, where Davis is incarcerated, 193 miles northwest of downtown Los Angeles.