Today the United States Supreme Court asks whether racism illicitly marred the trial of Miguel Peña-Rodriguez, who was convicted of assaulting two teenage sisters in Colorado. After the trial in 2010, two jurors told Mr Peña-Rodriguez’s lawyer that another juror said he was guilty “because he’s Mexican”. Racial bias is a “unique toxin” tainting the Sixth Amendment right of an impartial trial, Mr Peña-Rodriguez’s lawyers say. The state’s lawyers reply that scrutinising jurors’ comments after verdicts would “inhibit full and frank discussion in the jury room”. Better ways to vet a jury exist—such as checking their social-media posts. Colorado’s highest court ruled against Mr Peña-Rodriguez, finding that “the privacy of jury deliberations” is “sacrosanct”. Although the Supreme Court also takes this line, Justice Sonia Sotomayor noted in 2014 that “extreme” cases of juror bias could lead to a different outcome. Such a case may now be in the court’s hands.