FILE - In this Jan. 13, 2017 file photo California Supreme Court Associate Justice Goodwin Liu pauses in his office in San Francisco. The California Supreme Court justice says the death penalty system in the most populous state is dysfunctional, expensive and doesn't deliver justice in a timely way.  Liu made the comments in an unusual opinion issued Thursday, March 28, 2019, after the full court unanimously upheld Thomas Potts' death sentence. Potts was convicted in a 1997 killing of an elderly couple. (AP Photo/Jeff Chiu, File)

SAN FRANCISCO (AP) — The death penalty system in the nation's most populous state is dysfunctional and expensive, and a ballot measure approved by voters to speed up executions will not make it workable, a California Supreme Court justice said Thursday in an unusual opinion that added to a renewed debate about capital punishment.

Associate Justice Goodwin Liu made the comments two weeks after Democratic Gov. Gavin Newsom placed a moratorium on executions and said he is advocating for the repeal of capital punishment in California.

Liu said he was not expressing any view on the morality or constitutionality of the death penalty and would continue to uphold capital sentences when required by law. He joined the rest of the justices to unanimously affirm the death sentence of Thomas Potts, who was convicted of killing an elderly couple in 1997.

But in a separate opinion in that case, Liu expressed concerns about the death penalty system in California and Proposition 66, a 2016 ballot measure that aimed to remove regulatory hurdles to executions.

Voters narrowly approved the measure while rejecting a competing effort to ban the death penalty. The state Supreme Court upheld Proposition 66 in 2017, including Liu, who expressed some concerns in that decision but went further in his new opinion.

The measure did not enact the "key reforms that leading authorities consider fundamental to a workable death penalty system," Liu wrote in Thursday's opinion, which Associate Justice Mariano Florentino-Cuellar joined.

Former Democratic Gov. Jerry Brown appointed both justices.

The measure did not reduce the backup of direct death penalty appeals at the state Supreme Court or provide additional resources to appoint qualified attorneys for inmates or allow courts to expedite capital cases, Liu said.

Its promise that death penalty cases would be completely settled in the courts in five years was "more than the system can deliver," he said.

Without additional funding for the court system, the measure cannot reach its goals, Liu said.

He added that "the promise of justice in our death penalty system is a promise that California has been unable to keep" and a discussion on the effectiveness and cost of capital punishment was overdue.

Opponents say Proposition 66 does address the bottleneck of death penalty cases at the state Supreme Court by moving a big chunk of them to lower courts.

Kent Scheidegger, legal director of the Criminal Justice Legal Foundation, which has been fighting to force the state to resume executions, also disputed Liu's claim that the measure required additional funding.

"The notion that massive additional resources are the answer is a fabrication of the opponents created to bolster their argument that we should repeal the death penalty because it costs too much," he said in an email.

California has the nation's largest death row, with 737 inmates. Only 13 people have been executed since 1978 — the last in 2006. Condemned inmates are more likely to die of old age during decades of appeals.

Newsom praised Liu's opinion in a statement Thursday. When he signed the moratorium this month, the governor said the death penalty is applied unevenly and that innocent people can find themselves on death row.

He said he also may commute death sentences and is pushing to ban capital punishment. Fellow Democratic lawmakers introduced a ballot measure that would repeal the death penalty next year.

Critics, including President Donald Trump, accused Newsom of usurping voters' will. Some said his decision could face legal challenges.

In a poll released Thursday by the Public Policy Institute of California, just 38 percent of likely voters favored the death penalty when asked whether someone convicted of first-degree murder should get a death sentence or life in prison with no possibility of parole. 

File - In this Jan. 13, 2017, file photo, California Supreme Court Justice Goodwin Liu poses for photographs in his office in San Francisco. The California Supreme Court justice says the death penalty system in the most populous state is dysfunctional, expensive and doesn't deliver justice in a timely way.  Liu made the comments in an unusual opinion issued Thursday, March 28, 2019, after the full court unanimously upheld Thomas Potts' death sentence. Potts was convicted in a 1997 killing of an elderly couple. (AP Photo/Jeff Chiu, File)