But Newsom said that the death penalty is flawed because it is "irreversible and irreparable in the event of human error", and expensive, costing California $5 billion since 1978. A new execution protocol is under review, but Newsom's order will withdraw it.
The move is especially controversial considering that California voters rejected a ballot measure that would have repealed the death penalty in 2016. "The intentional killing of another person is wrong".
The president of the United States and the governor of California engaged in a game of "he said, he said" recently over whether Gavin Newsom's praise of Donald Trump included privately calling him "one of the smartest people I've ever met". This comes on the heels of Californians actually voting to bolster the speed with which the state can execute an inmate. But executions for more than 20 inmates who have exhausted their appeals could have resumed if those challenges were cleared up, and Newsom has said he anxious that it could happen soon. Republican Illinois Gov. George Ryan was the first to do so in 2000, though Illinois has since abolished the death penalty.
How did we get here? "At this time I don't see a legal challenge to the reprieve".
The governor's decision brings California in line with Colorado, Oregon, and Pennsylvania - all of which have governor-issued moratoria - and adds momentum to a national movement working to end capital punishment.
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But Newsom's action will anger death penalty proponents.
Newsom explained that he spoke to the president "because I wanted to extend to him my appreciation" for his visit to California areas hit by wildfires and to "express the fact that the people in those communities were grateful to him".
Mr Newsom is a Democrat who took office in January and a long-standing opponent of the death penalty, which was last carried out in California in 2006.
"He's following in the footsteps of other governors who abused this power because they were frustrated by a law that they just personally disagreed with", Scheidegger said.
Brown said he was satisfied with his record number of pardons and commutations, though he never attempted to commute a death sentence, and with his sweeping changes that eased criminal penalties while reducing the prison population. He also said innocent people have been wrongly convicted and sometimes put to death.
Newsom's aides said it has not yet been decided what will become of the execution chamber, or whether corrections officials have been told to top preparing for executions, for instance by running drills. "I've carved out my piece of all this".