"I hope never to see a case like this again," Sotomayor said.
Bongani Charles Calhoun, a black man, stood trial in Texas for a drug conspiracy. At issue was whether Calhoun knew the friend he was accompanying on a road trip, along with the friend's companions, were about to engage in a drug transaction.
When the others attempted to buy cocaine from an undercover federal agent, they were arrested.
At trial, Calhoun said he didn't know what the others were up to, and had detached himself from the group.
"The prosecutor pressed Calhoun repeatedly to explain why he did not want to be in the hotel room [with the others]," Sotomayor wrote. "Eventually, the ... judge told the prosecutor to move on. That is when the prosecutor asked, 'You've got African-Americans, you've got Hispanics, you've got a bag full of money. Does that tell you -- a light bulb doesn't go off in your head and say, 'This is a drug deal?'"
Sotomayor said Calhoun's lawyer didn't object at trial, and his petition to the Supreme Court cited the wrong grounds, leading the high court to reject it.
"There is no doubt, however, that the prosecutor's question never should have been posed," Sotomayor said. "Such argumentation is an affront to the Constitution's guarantee of equal protection of the laws. And by threatening to cultivate bias in the jury, it equally offends the defendant's right to an impartial jury."
She added: "By suggesting that race should play a role in establishing a defendant's criminal intent, the prosecutor here tapped a deep and sorry vein of racial prejudice that has run through the history of criminal justice in our nation. ... It is deeply disappointing to see a representative of the United States resort to this base tactic more than a decade into the 21st century. Such conduct diminishes the dignity of our criminal justice system and undermines respect for the rule of law. We expect the government to seek justice, not to fan the flames of fear and prejudice."