A federal US judge has ruled California's death penalty unconstitutional, writing that lengthy and unpredictable delays have resulted in an arbitrary and unfair system. The decision on Wednesday by US District Court judge Cormac Carney represents a legal victory for those who want to abolish the death penalty in the country's most populous state and follows a similar ruling that has suspended executions in the state for years. Carney, in a case brought by a death row inmate against the warden of San Quentin state prison, called the death penalty an empty promise that violates the constitutional protection against cruel and unusual punishment. "Inordinate and unpredictable delay has resulted in a death penalty system in which very few of the hundreds of individuals sentenced to death have been, or even will be, executed by the state," Carney wrote. Since the current death penalty system was adopted by California voters 35 years ago, more than 900 people had been sentenced to death, but only 13 had been executed, he wrote. The judge noted that death penalty appeals can last decades, and as a result most condemned inmates were likely to die of natural causes before execution. He wrote that "arbitrary factors, rather than legitimate ones like the nature of the crime or the date of the death sentence, determine whether an individual will actually be executed". Gil Garcetti, a former Los Angeles County district attorney who is now an anti-death penalty activist, called the ruling "truly historic". "It further proves that the death penalty is broken beyond repair," he said, calling for capital punishment to be replaced "with life in prison without the possibility of parole." Carney's ruling came in a legal petition brought by Ernest Dewayne Jones, sentenced to die in 1994 after being convicted of murdering and raping his girlfriend's mother.