He cited similar numbers for voter registration. Roberts later asked Solicitor General Donald Verrilli: "Is it the government's submission that the citizens in the South are more racist than citizens in the North?"
Verrilli replied simply, "It is not."
Kennedy raised another area of concern, whether state sovereignty was being undermined by what critics of Section 5 call onerous federal oversight.
"There is a federalism interest in each state being responsible to ensure that it has a political system that acts in a democratic and a civil and a decent and a proper and a constitutional way," he said. "But if Alabama wants to have monuments to the heroes of the Civil Rights Movement, if it wants to acknowledge the wrongs of its past, is it better off doing that if it's an own independent sovereign than if it's under the trusteeship of the United States government?"
The Obama administration points out that states have gotten out of Section 5. In recent years, 31 cities and counties and Virginia successfully petitioned to be exempt from the pre-clearance requirements, though the rest of the state remains under federal oversight.
Shelby County has not made such a request and opposes Section 5 on its face. It is 11 percent African-American, compared with 28 percent statewide.
The high court now may new be prepared to do what it hinted at in a separate Section 5 challenge three years ago.
Roberts authored that 2009 high court ruling, suggesting its days were numbered.
He said the pre-clearance provision raised "serious constitutional questions," and added it "represents an intrusion into areas of state and local responsibility that is unfamiliar to our federal system."
"Things have changed in the South. Voter turnout and registration rates now approach parity," said Roberts, echoing the views Shelby County now makes in its appeal. "Past success alone, however is not adequate justification to retain the pre-clearance requirements."
Until now, the court has avoided the key question over the law's constitutionality.
Some conservative groups have argued that "ancient formulas" are being applied today, not to erase discrimination, but to benefit a particular political party. Some liberal activists counter Section 5 and federal oversight are being demonized by many on the right for purely partisan gain, and to divide Americans again over race.
The case is Shelby County v. Holder (12-96).