The United States Supreme Court ruled Monday that non-unanimous jury decisions for criminal convictions are unconstitutional. Before the Court’s ruling, the practice of using split juries to determine a criminal conviction was only allowed in one state: Oregon.

In Oregon, jury verdicts where 10 jurors are in favor of conviction and two are against have been the minimum requirement for convictions in most criminal trials since state voters approved split-jury decisions in 1934. Until recently, Louisiana also allowed split juries, but the practice was ended by a successful statewide ballot measure in 2018. The Supreme Court's decision is based on Ramos v. Louisiana, a case that predates Louisiana's ballot measure, in which a Louisiana man argued that his own split-jury murder conviction in 2016 was unconstitutional. Today's 6-3 ruling against Louisiana means that all states must now require unanimous verdicts for criminal convictions.

The Court’s majority opinion rested on a fairly straightforward argument: The Sixth Amendment of the US Constitution guarantees the right to a fair trial, including unanimous jury convictions, at the federal level. Paired with the Fourteenth Amendment, which extends all federally guaranteed rights to the state level, lawyers argued that all state courts should have the same right to unanimous convictions.

“Wherever we might look to determine what the term ‘trial by an impartial jury trial’ meant at the time of the Sixth Amendment’s adoption… the answer is unmistakable,” wrote Justice Neil Gorsuch in the majority opinion. “A jury must reach an unanimous verdict in order to convict.”

Gorsuch was joined by Justices Sonia Sotomayor, Ruth Bader Ginsburg, Stephen Breyer, Clarence Thomas, and Brett Kavanaugh in ruling against split-jury convictions. Justices Samuel Alito and Elena Kagan, and Chief Justice John Roberts, dissented on the grounds that the decision disrupted established precedent.

In the majority opinion, Gorsuch also noted that Oregon’s and Louisiana’s split-jury practices could be traced back to racist politics of the 20th Century. In Louisiana, it was a holdover from Jim Crow-era laws in the South.

“Adopted in the 1930s, Oregon’s rule permitting non-unanimous verdicts can be similarly traced to the rise of the Ku Klux Klan and efforts to dilute ‘the influence of racial, ethnic, and religious minorities on Oregon juries,’” Gorsuch wrote, quoting from another Oregon court case. “In fact… courts in both Louisiana and Oregon have frankly acknowledged that race was a motivating factor in the adoption of their States’ respective non-unanimity rules.”

Race continues to be a factor in split-jury decisions to this day. In 2018, Louisiana newspaper The Advocate found that split-jury decisions in the state impacted Black defendants at a much higher rate than they did white defendants.

Criminal justice organizations across Oregon have applauded the court's decision.

“The Supreme Court today struck down Oregon’s racist and shameful law that allowed people to be convicted by a 10-2 jury," said Kelly Simon, interim legal director at ACLU of Oregon, in a press release. "Non-unanimous jury verdicts silenced minority voices, amplified implicit bias, and perpetuated racial disparities."

The court’s ruling will affect how Oregon’s criminal trials proceed in the future—but it could also impact the fate of people already convicted by split juries. Oregon Attorney General Ellen Rosenblum submitted a legal brief to the Supreme Court last year, asking it to rule in favor of Louisiana. Rosenblum warned that a ruling like the one the Court delivered Monday could “require new trials in hundreds, if not thousands, of cases,” and would overwhelm the state’s court system. Rosenblum has said she supports getting rid of split-jury convictions, but would prefer doing so by state ballot measure, so that the specifics could be more tightly controlled by Oregon leaders.

Aliza Kaplan, a law professor at Lewis & Clark and a co-founder of the Oregon Innocence Project, told the Mercury last year that Rosenblum’s prediction was likely overblown—and that the state should be more concerned with ensuring its convictions were just.

“The Constitution should always trump any administrative inconvenience or burden,” she said. “This is about preserving individual rights and liberties.”

In any event, Roseublum’s argument wasn’t enough to persuade the Court to rule in Louisiana’s favor.

“The fact that Louisiana and Oregon may need to retry defendants convicted of felonies by non-unanimous verdicts whose cases are still pending on direct appeal will surely impose a cost,” reads a summary of the majority opinion. "But new rules of criminal procedure usually do.”