The trial in Commonwealth Court begins almost a year after Judge Robert E. Simpson Jr. agreed to bar enforcement of the photo ID law in last November's presidential election. He held off enforcing it in the May 21 primary as well, in anticipation of giving the plaintiffs their day in court.
Their lawyers will face an arguably sympathetic foe in court: the office of state Attorney General Kathleen Kane. In her 2012 campaign, Kane was one of many Democrats who attacked the voter ID law.
Amid questions following her Thursday announcement that she would not defend the state's same-sex marriage ban, Kane's office issued a statement saying its staff lawyers would represent the state in the voter ID case.
She inherited the voter case from her Republican predecessor as attorney general, Linda Kelly, and was drawn into the lawsuit filed Monday in federal court seeking to overturn the 1996 Defense of Marriage Act.
In a statement, Kane explained why she could defend one law but not the other.
"The Pennsylvania voter ID law is, on its face, constitutional," she said. "My concern with the voter ID law has always been its implementation."
The law, championed by its Republican sponsors in the legislature as a defense against voter fraud, was signed in March 2012 by Gov. Corbett. Democrats and civil rights groups contended it would result in disenfranchisement of many minority, elderly, or disabled voters who could not obtain proper ID because they lacked the supporting documents required by the law.
State officials conceded last year in court that they had no evidence of voter fraud in Pennsylvania. They argued that such evidence was not necessary to prove the law's worth.
Lawyers for the plaintiffs say they will try to prove that individuals who voted last Nov. 6 would not have been able to do so had the photo-ID mandate been in effect.
"Real people voted in November who don't have valid ID and can't get one," said Marian Schneider, a lawyer with the Advancement Project, during a conference call Friday with reporters.
She said her side would offer provide testimony from residents who cannot get to a state Department of Transportation facility, and from a woman who did not vote in the May primary because thought she needed photo ID.
"What all these voters have in common is that they are real people . . . and don't have one of limited forms of acceptable ID, and they will be disenfranchised by this law," Schneider said.
Under the law, the only acceptable forms of ID are those authorized by the state, such as driver's licenses. The Department of State, which oversees elections, last year created a special photo ID card for voting. The state has issued about 17,000 of those cards.
The state has done a poor job in its campaign to notify people about the new law and made it difficult for many people to get the proper ID, contended Witold J. Walczak, legal director of the ACLU of Pennsylvania. Seventy-one PennDot centers issue identification cards. Nine counties have no PennDot facility, and 11 have offices that are open only one day a week, he said.
Department of State spokesman Ron Ruman said this month that officials had done all they could to ensure voters could obtain a valid ID.
The state spent $5 million in federal money set aside for voter education on the voter ID awareness campaign.
The plaintiffs say the state's own data on drivers' licenses and PennDot-issued photo ID cards, made public last summer amid debate over the new law, show that voters who possessed neither numbered in the hundreds of thousands.
Given the court schedule and likelihood of appeals in the lawsuit, there is a strong possibility that the photo ID requirement will not be in effect this fall.
The plaintiffs' lawyers are asking the court to bar enforcement until the case has been fully resolved, most likely after the Nov. 5 judicial and municipal elections.
"No one thinks this will be decided before the November election," said Jennifer Clarke, executive director of the law center.
The trial is expected to take up to eight days, she said.
CORRECTION: This story was updated to correct Marian Schneider's affiliation. She is an attorney with the Advancement Project.
Contact Amy Worden at 717-783-2584 or firstname.lastname@example.org or follow @inkyamy on Twitter.