And by confining the decision to the upcoming presidential election, Commonwealth Court Judge Robert Simpson Jr. ensured that the debate will continue in Pennsylvania.
Richard Hasen, professor of law and political science at the University of California, Irvine, said Simpson and the state Supreme Court seem to agree that requiring voter ID is allowed, as long as it is implemented fairly.
"There seems little controversy about having an ID requirement in place once there is time for everyone to get the documentation," he said.
But Keesha Gaskins, senior counsel for the Democracy Program at New York University's Brennan Center for Justice, which has opposed the law, said Simpson's ruling was just the latest example of such regulations being "overturned and pushed back in state after state after state."
While voter ID has become law in many places, the rules vary greatly. Some states require as little as a utility bill for documentation while others demand a photo ID.
In 2008, the U.S. Supreme Court upheld Indiana's voter-ID law. That decision emboldened many states to enact similar laws.
Some states, most of them in the South, have such a strong history of voting discrimination that they must get approval, known as "preclearance," from the U.S. Department of Justice for changes to election laws.
The Justice Department did not grant Texas preclearance for its new voter-ID law, and in late August, a federal panel of judges confirmed that decision, finding that long drives and fees required to get identification in the Lone Star State would discriminate against minorities.
A less stringent ID law, which requires non-photo identification and allows those without it to cast provisional ballots, remains in effect in Texas.
Battles also are raging in some states that don't require preclearance.
In March, a state judge overturned a new voter-ID law in Wisconsin, ruling that it disenfranchised voters. As a result, the law won't take effect in November.
In Minnesota, Republican majorities in the House and Senate passed a bill in 2011 requiring voters to show photo ID, but Democratic Gov. Mark Dayton vetoed it.
State Republicans fought back. Minnesota voters will decide by referendum in November whether the state should enact photo ID going forward.
Even if the measure passes, Minnesota legislators could still wrangle over the details, which will require the Democratic governor's signature.
Hasen and other experts believe the voter ID battle will continue to be fought on partisan lines unless the country can agree to implement some form of national ID program.
Robert A. Pastor, codirector of the Center for Democracy and Election Management at American University, who was executive director of a 2005 bipartisan commission examining the U.S. election process, said only a national ID program would inhibit voting fraud. When laws are passed state by state, voters with homes in more than one place can cast ballots twice - locally and by absentee ballot, he said.
"I don't think that each state alone can implement effective voter identification," he said.
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