In an opinion piece published by the Washington Post Tuesday headlined "It's time for Louisiana to strip white supremacy from its constitution," the singer writes about the state's continued acceptance of non-unanimous jury decisions, which he calls "a 120-year-old measure put in place to suppress the rights of African Americans.""Louisiana is one of only two states — the other is Oregon — in which a person can be convicted of a felony and sent to prison without a unanimous vote of the jury," Legend wrote. "As a result, Louisiana prosecutors do not truly have the burden of proving their case 'beyond a reasonable doubt.' They only need to persuade 10 of 12 jurors to send a defendant to prison, even for life."According to the star, the result is "a state justice system in which felony trials are held without the full participation of African Americans.""Here's why: During Louisiana's all-white constitutional convention in 1898, delegates passed a series of measures specifically designed to 'perpetuate the supremacy of the Anglo-Saxon race in Louisiana,'" the piece states. "Non-unanimous juries were one of those measures, and the intent was clear: If the federal Constitution required that African Americans be allowed to serve on juries, the state constitution would make sure that minority votes could be discounted."Voters in Louisiana will be asked in November if they want to amend the state's constitution to remove the clause that allows non-unanimous jury decisions.Legend is the founder of the criminal justice reform advocacy group FreeAmerica and has been outspoken on several issues, including mass incarceration, immigration and racial injustice.Related: John Legend urges protesters to resist 'temptation to just disengage'Last year, the Grammy winner visited Baton Rouge to offer his support for criminal justice reform in Louisiana. Now he said he hopes people will support this "non-partisan" ballot issue to strike down non-unanimous decisions by juries."It's time to come together, reject prejudice in all its forms and build a future in which everyone is valued and supported," Legend wrote. "The 1898 constitutional convention was about denying voice to the expression of all of Louisiana's citizens. This ballot question in November is about giving Louisiana her voice back."