The Supreme Court of Washington in a Thursday ruling declared the state's capital punishment regime incompatible with its constitution.

The ruling came in the case of State v. Gregory, the Associated Press reports. The court ordered Allen Eugene Gregory's sentence, and the sentences of the other seven men on death row, converted into life in prison.

Gregory, according to the AP, was convicted in 1996 of the rape, robbery, and murder of 43-year-old Geneine Harshfield. But, the court found, "the death penalty is invalid because it is imposed in an arbitrary and racially biased manner," and thereby runs afoul of the state's constitution.

Washington now becomes the 20th state in the Union without the death penalty. Gov. Jay Inslee (D., Wash.), a one-time capital punishment supporter, declared a moratorium on capital punishment in the state under his tenure upon taking office. In a statement, Inslee heralded the court's decision as a "hugely important moment."

"Today's decision by the state Supreme Court thankfully ends the death penalty in Washington. The court makes it perfectly clear that capital punishment in our state has been imposed in an ‘arbitrary and racially biased manner,' is ‘unequally applied' and serves no criminal justice goal. This is a hugely important moment in our pursuit for equal and fair application of justice," Inslee said.

The American Civil Liberties Union, which routinely litigates against the death penalty, also celebrated a victory for abolitionists.

"The Washington State Supreme Court today declared the state's scheme of capital punishment unconstitutional on the ground that it is infected with racial bias that influences the decisions about who should live and who should die," said Jeff Robinson, deputy legal director Trone Center for Justice at the American Civil Liberties Union. "There is nothing unique about the role racism played in Washington's death penalty. What is rare is the Supreme Court's willingness to call out the truth that has always been there."

Research has routinely found that prosecutors are not more likely to seek the death penalty for black murderers than for white ones, although cases with white victims are more likely to result in a death sentence.

It remains to be seen how final the Supreme Court of Washington's ruling will be. In 2014, a federal judge found the death penalty unconstitutional in California as then constituted—voters subsequently backed a referendum to fix the penalty, although litigation surrounding its implementation is still on-going.