Washington became the 20th U.S. state to abolish capital punishment when its Supreme Court struck down the death penalty on Thursday, saying in a unanimous decision that its application was arbitrary and racially biased.
"The death penalty, as administered in our state, fails to serve any legitimate enological goal," the Washington Supreme Court said, adding it "is invalid because it is imposed in an arbitrary and racially biased manner."
After the court decision, Democratic Governor Jay Inslee tweeted, "Equal justice is a hallmark of democracy and assuring equal justice is the state's responsibility. I've long been convinced that the death penalty in the state of Washington does not pass that test."
Capital punishment has been on the decline in the United States for several years, but the Administration of Republican President Donald Trump has said it is considering expanding its use for some federal crimes.
In 2016, the Delaware Supreme Court abolished the death penalty.
Opponents have said there is no consistent method for prosecutors to decide in which cases they will seek capital punishment, arguing that such decisions are often made for political reasons.
The Washington court analyzed use of the death penalty in the state over the decades and found that it was imposed in an "arbitrary and capricious manner" with racial bias built into the system.
Washington, which has executed five inmates since the U.S. Supreme Court reinstated the death penalty in 1976, placed a moratorium on executions in 2014. Its eight prisoners on death row are now serving life sentences.
At the time, Inslee said that the majority of the state's death penalty sentences were overturned and those people convicted of capital offences were rarely executed, indicating questionable sentencing in many cases.
Death penalty supporters have argued that it needs to stay on the books to serve as punishment for those who commit the most heinous crimes.
There were 23 executions in the United States in 2017, down from a peak of 98 in 1999, according to the Death Penalty Information Center, which monitors U.S. capital punishment.
Robert Dunham, the centre's executive director, noted that Thursday's decision by the Washington state court did not address whether the death penalty was immoral.
Instead, he said, it argued, "it has been impossible for Washington to administer it fairly."
(With inputs from agencies.)