Clement will be joined in defending South Carolina by Christopher Bartolomucci, a White House lawyer under Bush. Both men work for the Bancroft firm, a prominent Washington legal group that focuses on cases likely to go to federal appellate courts or the U.S. Supreme Court.

Regardless of how the three-judge panel rules, the S.C. law is expected to end up before the U.S. Supreme Court. The high court also is likely to decide the fate of a Texas state photo ID law. After a trial last month, a panel of federal district judges has not yet ruled on that law.

To rebut the claim of racial progress in South Carolina, lawyers for civil rights groups, which oppose the photo ID law, filed a list of 21 cases, going back to 1980, in which federal courts found evidence of racial discrimination in the state. Among the groups are the NAACP, the American Civil Liberties Union and the Lawyers’ Committee for Civil Rights Under Law.

Among 30 people expected to testify are S.C. House Speaker Bobby Harrell, R-Charleston; Lt. Gov. Glenn McConnell, R-Charleston; Marci Andino, executive director of the State Election Commission; Kevin Shwedo, executive director of the S.C. Department of Motor Vehicles; and Barbara Zia, head of the S.C. League of Women Voters.

Perez of the Justice Department will argue that white male S.C. legislators excluded their black counterparts from deliberations on the photo ID bill and ignored their concerns.

“African-American legislators in the (S.C.) House had no meaningful input,” Perez wrote in his brief. “Compromises struck with African-American senators were repeatedly gutted, as the provisions they sought to have included in the bill – acceptance of government employee IDs, exemptions for the elderly, and early voting – were stopped.”

The trial also will see dueling experts, each bringing reams of election, voting and demographic data.

The state’s star witness, University of Georgia political scientist Trey Hood, will testify that the photo ID law would produce “no legally disparate impact on minority voters.”

The Justice Department will call Charles Stewart, a political scientist at Massachusetts Institute of Technology, and Ted Arrington, a political science professor emeritus at UNC-Charlotte. Stewart will testify that the law would “impose disproportionate burdens on minority voters ... that do not currently exist under South Carolina law.” Arrington will testify that the photo ID law “was enacted with a racially discriminatory purpose.”

The intervening civil rights groups will call three scholars, among them Clemson University history professor Orville Vernon Burton, who will testify that the law is intended to suppress the strength of the African-American vote.

Also testifying will be several S.C. voters who will say the law would make it more difficult for them to cast ballots.

Based on its pretrial brief, South Carolina’s case rests heavily on a 2008 U.S. Supreme Court decision that upheld an Indiana voter ID law.

In that 6-3 ruling, Justice John Paul Stevens, who led the high court’s liberal wing until his 2010 retirement, said that law would burden only a small share of voters, burdens offset by Indiana’s need to prevent electoral fraud.

“Because Indiana’s cards are free, the inconvenience of going to the Bureau of Motor Vehicles, gathering required documents and posing for a photograph does not qualify as a substantial burden on most voters’ right to vote, or represent a significant increase over the usual burdens of voting,” Stevens wrote.

Clement noted South Carolina’s law partly was modeled on the Indiana law, providing provisional ballots to voters without photo IDs if they sign an affidavit.