Quoting Pope Francis' words in a speech of Oct. 11, 2017, the section now states, in part, that "the Church teaches, in the light of the Gospel, that 'the death penalty is inadmissible because it is an attack on the inviolability and dignity of the person,' and she works with determination for its abolition worldwide."
Reasons for the change, the paragraph says, include the increasing effectiveness of detention systems; growing understanding of the unchanging dignity of the person; and leaving open the possibility of the prisoner's conversion.
Defense lawyers have argued that Washington state's worst mass murderers and serial killers had received life sentences instead of the death penalty, highlighting this as proof of arbitrary application of capital punishment.
Other death penalty critics drew on University of Washington sociologists' findings, the Associated Press reported. While prosecutors are not more likely to seek the death penalty when the defendant is African-American, juries were about four times more likely to favor imposing the death penalty on black defendants.
Four other justices on the court concurred with the majority conclusion in a separate decision saying that other state constitutional factors "compel this result."
Republican State Sen. Mike Padden had previously voted against death penalty repeal and was critical of the Supreme Court decision. While capital punishment should be rarely used, he said, "I do think it should be an option in the most heinous cases."
Hannah Cox, national manager of Conservatives Concerned About the Death Penalty, was among the supporters of the decision.
"This decision will save Washington state taxpayers millions of dollars that would otherwise be wasted," Cox said. "Conservatives in Washington state and across the country increasingly realize the death penalty is a failed government program that does not value life, threatens innocent people, and wastes money."
The court's majority decision left open the option for the legislature to enact a "carefully drafted statute" allowing the death penalty but said it cannot create "a system that offends constitutional rights."
State Attorney General Bob Ferguson said he would propose legislation to repeal the death penalty and replace it with life in prison without the possibility of parole.
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"We should act quickly to remove the death penalty from state law once and for all," he said in a statement.
Washington Gov. Jay Inslee had imposed a moratorium on the death penalty in 2014.
Robert Dunham, executive director of the Washington, D.C.-based Death Penalty Information Center, told the Associated Press the use of the death penalty is becoming "increasingly geographically isolated" in southern and southwestern states.
Texas has executed 108 prisoners since 2010, the most of any state. Florida has executed 28 over the same period, followed by Georgia and Oklahoma as the next most common users of capital punishment.
While court decisions, legislative actions or moratoria have halted the death penalty in many states, New Hampshire and Nebraska voters have overturned such decisions by veto or referendum.
Editorial Note: This story has been updated with additional content.