California Code, Penal Code - PEN § 3049.5

Notwithstanding the provisions of Section 3049, any prisoner selected for inclusion in a specific research program approved by the Board of Corrections may be paroled upon completion of the diagnostic study provided for in Section 5079. The number of prisoners released in any year under this provision shall not exceed 5 percent of the total number of all prisoners released in the preceding year.

This section shall not apply to a prisoner who, while committing the offense for which he has been imprisoned, physically attacked any person by any means. A threat of attack is not a physical attack for the purposes of this section unless such threat was accompanied by an attempt to inflict physical harm upon some person.