The 737 inmates on California's largest-in-the-nation death row are getting a reprieve from Governor Gavin Newsom, who plans to sign an executive order on Wednesday placing a moratorium on executions. Mr Newsom also is withdrawing the lethal injection regulations that death penalty opponents already have tied up in courts and shuttering the new execution chamber at San Quentin State Prison that has never been used. "The intentional killing of another person is wrong and as governor, I will not oversee the execution of any individual," he said in prepared remarks. Mr Newsom called the death penalty "a failure" that "has discriminated against defendants who are mentally ill, black and brown, or can't afford expensive legal representation". He also said innocent people have been wrongly convicted and sometimes put to death. California hasn't executed anyone since 2006, when Arnold Schwarzenegger was governor. And though voters in 2016 narrowly approved a ballot measure to speed up the punishment, no condemned inmate faced imminent execution. Since California's last execution, its death row population has grown to house one of every four condemned inmates in the United States. They include Scott Peterson, whose trial for killing his wife Laci riveted the country, and Richard Davis, who kidnapped 12-year-old Polly Klaas during a slumber party and strangled her. Mr Newsom "is usurping the express will of California voters and substituting his personal preferences via this hasty and ill-considered moratorium on the death penalty," said Michele Hanisee, president of the Association of Deputy (Los Angeles County) District Attorneys. But Alison Parker, US managing director at Human Rights Watch, praised Newsom's "great courage and leadership in ending the cruel, costly and unfair practice of executing prisoners," calling for other states to follow California's lead. The American Civil Liberties Union called it "a watershed moment in the fight for racial equity and equal justice for all." Justin Brooks, director of the California Innocence Project, lauded Newsom for ending the risk of executing someone who is innocent. Kent Scheidegger, legal director of the Criminal Justice Legal Foundation, which has been fighting in court to force the state to resume executions, said blocking Mr Newsom's move may be difficult. "Reprieves, the governor does have the power to do that. That doesn't make it the right thing to do," Mr Scheidegger said. "At this time, I don't see a legal challenge to the reprieve." However, he said prohibiting corrections officials from preparing to carry out executions "is patently illegal" under the 2016 ballot measure. Stanislaus County District Attorney Birgit Fladager, president of the California District Attorneys Association, also criticised Mr Newsom for circumventing the will of a majority of voters. But he had support from Democratic lawmakers including Sen. Scott Wiener of San Francisco and Assemblywoman Lorena Gonzalez of San Diego, who praised Mr Newsom for doing "what's right, even when it's tough," in Ms Gonzalez's words. Aides said Mr Newsom's power to grant reprieves is written into the state Constitution and that he is not altering any convictions or allowing any condemned inmate a chance at an early release.