By MATT APUZZO

WASHINGTON — Civil rights groups have spent a decade fighting requirements that voters show photo identification, arguing that this discriminates against African-Americans, Hispanics and the poor. This week in a North Carolina courtroom, another group will make its case that such laws are discriminatory: college students.

Joining a challenge to a state law alongside the N.A.A.C.P., the American Civil Liberties Union and the Justice Department, lawyers for seven college students and three voter-registration advocates are making the novel constitutional argument that the law violates the 26th Amendment, which lowered the voting age to 18 from 21. The amendment also declares that the right to vote “shall not be denied or abridged by the United States or any state on account of age.”

There has never been a case like it, and if the students succeed, it will open another front in what has become a highly partisan battle over voting rights.

Over the past decade, Republicans have campaigned to tighten rules for voters, including requirements for photo ID, in the name of preventing fraud. Democrats have countered that the real purpose of those laws is to make voting more difficult for people who are likely to vote Democratic.

Josue Berduo, a student at North Carolina State University and a plaintiff in a novel legal challenge, said a new law in North Carolina was making “what should be a simple process very difficult.”

“There’s an unprecedented effort nationally by Republican-controlled legislatures to restrict the franchise in a way we haven’t seen in a long time,” said Marc Elias, the Democratic election lawyer bringing the age-discrimination claim. “Young voting in particular is a part of that effort.”

Proposals to change voting rules have frequently affected younger voters, particularly college students.

In Ohio, legislators proposed a law that would have cost colleges millions of dollars for helping out-of-state students vote locally. The measure died amid criticism from state schools. In Maine, the Republican attorney general — at the behest of the state party chairman — investigated 200 students for fraud. After finding no evidence, he sent the students a letter warning them to register their cars in Maine or to cancel their voter registrations.

In Texas, voters must show a photo ID. A state handgun license qualifies, but a state university identification card does not. North Carolina students have also complained of government efforts, distinct from the new voting law, to shut down voting sites at Appalachian State University and Winston-Salem State University.

Under the North Carolina law passed last year, the period for early voting was shortened and same-day registration was eliminated. Beginning in 2016, voters will need to show photo identification, and student ID cards, including those issued by state universities, will not be acceptable. In most instances, neither will an out-of-state driver’s license.

The law also eliminated a program in which teenagers filled out their voter-registration forms early and were automatically registered when they turned 18.

“For people like me, it makes what should be a simple process very difficult,” said Josue Berduo, 20, an economics major at North Carolina State University and a Democrat who is one of the plaintiffs.

Mr. Berduo, who is from Asheville, N.C., has a state identification card. But many students do not, he said, and no matter how much attention the law gets, some students will be unaware of the changes and will arrive at polling places carrying out-of-state licenses or student identification cards.

Jeff Tarte, a Republican state senator who supported the voter-ID law, said lawmakers did not intend to keep younger voters away from the polls. He said they were trying to prevent students from submitting absentee ballots in their home states and also voting in North Carolina. “Not that they would necessarily,” he said, “but why even offer that possibility to occur?”

But it is hard to separate the voting rights battle from the larger political struggle that has been underway in North Carolina since President Obama carried the state in the 2008 election and Democrats trumpeted it as evidence the state was turning blue. A Republican resurgence in the years since has resulted in, among other things, a deeply conservative legislature and a Republican governor, Pat McCrory, and has made Kay Hagan, a Democrat, one the United States Senate’s most endangered incumbents in this fall’s election.

Nationally, voters under the age of 30 represent a big voting bloc. They cast more than 20 million votes in the 2012 presidential election, accounting for about 15 percent of the total, according to the Center for Information and Research on Civic Learning and Engagement, a nonpartisan center at Tufts University. And in North Carolina, their turnout in 2012 was about 57 percent, among the highest in the country.

In both that election and in 2008, the Obama campaign pushed hard to register student voters, and the payoff was clear. In 2008, that age group voted so overwhelmingly for Mr. Obama that he became the first Democratic presidential candidate in a generation to carry the state, though he lost every other age group. Four years later, young voters helped keep the election close, though Republican Mitt Romney carried the state.

The North Carolina legislature passed its voter-identification law against a backdrop of the nationwide effort by Republicans to tighten a process that they see as ripe for abuse. While no evidence of widespread voting fraud has been uncovered, the movement has highlighted the shoddy state of the voting rolls. A 2012 report by the Pew Center on the States found 1.8 million dead people listed as voters nationwide and about 2.75 million people who were registered to vote in more than one state.

“While some will try to make this seem to be controversial, the simple reality is that requiring voters to provide a photo ID when they vote is a common-sense idea,” Governor McCrory said after signing the law.

The Supreme Court has held that voter-identification laws, in general, are constitutional. But the details, and how they are put in effect, can still be challenged. The Justice Department is fighting a similar law in Texas. Pennsylvania’s law was struck down in court, and the state opted not to appeal. Several other court cases continue.

Multiple lawsuits against North Carolina, including the age-discrimination case, have been combined into one. A hearing on Monday is over whether to delay the law until a judge decides whether it is constitutional.

Lawyers for the students believe they can make the case that the law is intentionally discriminatory. As proof of this intent, they note that the state prohibited the Division of Motor Vehicles from registering 17-year-olds who will turn 18 by Election Day this fall. All other eligible voters could register there. In court documents filed in late June, the state said it had reversed that policy but did not say why.

The lawyers also point to the state’s decision to allow military and veteran identification cards, but not student IDs, as “strong evidence that the legislature wanted to make it difficult for young citizens to vote.”

Lawyers for North Carolina argue that the state’s voting law is neither discriminatory nor an impediment to voting. They note that most of the law’s provisions have taken effect, and state election data showed no decline in minority turnout in the recent primary.

“One way of maintaining confidence in elections is to ensure that only those who are qualified to vote are actually registered to vote,” the state’s lawyers wrote in court documents. They did not address the 26th Amendment claim, and a phone call seeking comment on it was not returned.

While courts have held that refusing to register students is as unlawful as refusing to register African-Americans, they have never been asked to address allegations of more subtle age discrimination, like those charged in North Carolina.

“If that’s a winning claim, that’s a big deal,” said Edward B. Foley, an Ohio State University law professor who runs the school’s election law center. But, he said, “there is a big ‘if’ here.”