Can't really say I've paid a lot of attention to the death penalty status in California for the last few decades, so I found this illuminating
article:
Legal challenges and changes
Beginning in 1967, as a result of various state and United States Supreme Court decisions, there were no executions in California for 25 years.
In February 1972, the California Supreme Court found that the death penalty constituted cruel and unusual punishment under the California state constitution and 107 condemned inmates were resentenced to life with the possibility of parole and removed from California’s death row.
In 1973, the United States Supreme Court held that the death penalty was unconstitutional as it was being administered at that time in a number of states.
In November 1972, the California electorate amended the state constitution and in 1973, legislation was enacted making the death penalty mandatory in specified criminal cases. Among these were kidnapping if the victim dies, train wrecking if any person dies, assault by a life prisoner if the victim dies within a year, treason against the state, and first-degree murder under specific conditions (for hire, of a peace officer, of a witness to prevent testimony, if committed during a robbery or burglary, if committed during the course of a rape by force, if committed during performance of lewd and lascivious acts upon children, by persons previously convicted of murder).
In 1976, the California Supreme Court, basing its decision on a United States Supreme Court ruling earlier that year, held that the California death penalty statute was unconstitutional under the U.S. Constitution because it did not allow mitigating circumstances to be admitted as evidence. Following this ruling, 70 inmates had their sentences changed to other than death.
Capital punishment reinstated
The California State Legislature re-enacted the death penalty statute in 1977. Under the new statute, evidence in mitigation was permitted. The death penalty was reinstated as a possible punishment for first-degree murder under certain conditions. These special circumstances include: murder for financial gain, murder by a person previously convicted of murder, murder of multiple victims, murder with torture, murder of a peace officer, murder of a witness to prevent testimony and several other murders under specified circumstances.
In 1977, the Penal Code also was revised to include the sentence of life imprisonment without the possibility of parole. At that time, the punishment for kidnapping for ransom, extortion or robbery was changed from death to life without parole. Treason, train derailing or wrecking, and securing the death of an innocent person through perjury became punishable by death or life imprisonment without parole.
California voters approved Proposition 7 in November 1978, reaffirming the death penalty in California. It superseded the 1977 statutes and is the death penalty statute under which California currently operates.
Personally I would support a referendum to abolish the death penalty.
They just don't want truckloads of negative PR from an activity with no profit.