"Over time, more states that are not executing anyone may reconsider the considerable expense of the death penalty as not a worthwhile use of resources," he told the Washington Post.
Archbishop Jose Gomez of Los Angeles praised California's decision, hailing it as a pro-life move that is good for the state and the nation.
"Every human life is precious and sacred in the eyes of God and every person has a dignity that comes from God. This is true for the innocent and it is true for the guilty. It is true even for those who commit grave evil and are convicted of the most cruel and violent crimes," said Gomez.
The Death Penalty Information Center said that numerous cases in 2019 involved mental illness or an error in the legal process.
"Those sentenced to death this year included defendants whose juries did not unanimously recommend a death sentence, a brain-damaged defendant who was permitted to represent herself, a foreign national who waived his right to consular assistance, and others who waived their right to counsel, waived their right to a jury trial, and/or pled guilty and presented no case for life," the organization said.
It added that two men on death row - both convicted in the 1970s - were exonerated in 2019, bringing the number of exonerations since 1973 to 166. Clifford Williams Jr. was released from Florida's death row in March and Charles Ray Finch was released from prison in North Carolina in June.
For the World Day Against the Death Penalty in October, three U.S. bishops encouraged mercy during a live video stream. Archbishop Wilton Gregory of Washington emphasized the cases of people who have been found innocent through new evidence or modern DNA testing.
"With the death penalty, there are no re-tries. It concludes and ends a life that may have been wrongly [convicted]," Gregory said.
"The Gospel calls us to mercy. Mercy is never cruel," he added.