"Our death penalty system has been-by any measure-a failure", Newsom added. In addition, said Newsom, people with brain injuries, intellectual disabilities and serious childhood trauma comprised "18 of the 25 people executed in the U.S.in 2018".
"It's not an abstract question any longer", he said.
Newsom, who appeared emotional during the news conference, said he had met relatives of victims in recent days and acknowledged they were divided on the issue.
"I can not sign off on executing hundreds and hundreds of human beings".
Prison staff remove the electric chair from San Quentin, March 13, 2019, after Gov. Gavin Newsom placed a moratorium on the death penalty.
"Governor Newsom has demonstrated great courage and leadership in ending the cruel, costly, and unfair practice of executing prisoners", said Alison Parker, US managing director at Human Rights Watch. A future governor would have the power to change their fate. By signing his executive order, Newsom will lower the country's death row population by a quarter.
"The intentional killing of another person is wrong and as Governor, I will not oversee the execution of any individual", said Governor Newsom.
His move is part of a larger swing in California away from tough-on-crime policies.
However, Newsom has also garnered the support of politicians, celebrities and advocates. Earlier this week, Jaime Osuna, a convicted murderer who was spared the death penalty for the gruesome torture and murder in 2011 of Yvette Pena, a mother of six - and who mocked her family in court - was suspected of murdering his cellmate, who was found dead over the weekend.
"As a career law enforcement official, I have opposed the death penalty because it is immoral, discriminatory, ineffective, and a gross misuse of taxpayer dollars", she said in a statement.
Despite the temporary ban on capital punishment, no death row inmates are to be released as a result of this move.
"It's improper for an executive to use the reprieve power to frustrate the people's position".
Stanislaus County District Attorney Birgit Fladager, president of the California District Attorneys Association, also criticized Newsom for circumventing the will of a majority of voters.
"There is really nothing we can do about what the governor does", Oceanside police spokesman Tom Bussey said Wednesday.
On Wednesday, Assemblyman Marc Levine proposed giving Californians yet another chance to weigh in: the San Rafael Democrat is introducing a constitutional amendment that would abolish capital punishment if approved by voters in 2020. "I think if someone kills, we don't kill". "How do we administer justice properly?"
"I hope that is consistent with the expectation of the many who have elected me previous year". They have been lobbying Newsom to do the same since he was sworn-in in January.
A governor needs approval from the state Supreme Court to pardon or commute the sentence of anyone twice convicted of a felony, and the justices a year ago blocked several clemency requests by former Gov.