SEATTLE — Two years ago, when Washington’s Supreme Court was reviewing the death sentence assigned to a black man accused of raping and murdering a 65-year-old woman, Justice Charles Wiggins found himself troubled by numbers.

Juries in the state were more likely to sentence African Americans, Wiggins noted; they did so in 62 percent of cases involving black defendants versus 40 percent for white defendants. In a dissenting opinion, the justice suggested further study was needed to determine whether the trend was statistically significant.