The North Carolina voting law at the center of a federal court decision this week has a curious distinction: Statistics suggest it is an unnecessary solution to an invented problem that has had no discernible effect.

And yet it has driven partisans on both sides wild.

Welcome to the weird world of voter identification laws. North Carolina is at the epicenter of a political firestorm that has evolved to be more about partisan talking points than actual facts, some analysts say.

To Republicans, 19 states have passed voter ID laws to protect the sanctity of American democracy, ensuring that those who vote are actually who they say they are.

To Democrats, these voter ID laws are veiled attempts by red states to make it harder to vote, driving down turnout among minorities who tilt overwhelmingly Democratic.

There's truth to both sides – but not as much as the rhetoric might suggest. In that way, the North Carolina law is a window into how partisan politics can skew an issue, not only obscuring the data, but also driving up the rhetorical volume to levels perhaps disproportionate to the problem.

And in that way, it is a lesson, says Steven Greene, a political scientist at North Carolina State University in Raleigh. Sometimes, "in politics, reality doesn't matter, perception matters."

Voter fraud and lightning strikes

The issue came to a head this week because a federal district judge, Thomas Schroeder, issued a 485-page decision that upheld all of the new voting rules passed by North Carolina in 2013. The decision was closely watched nationwide because North Carolina's law is particularly aggressive – ending same-day registration, shortening a month-long early voting period by a week, and stopping voters from casting ballots outside of their precincts.

In upholding the law, however, the judge effectively accepted both sides' arguments. He acknowledged that the law represented a "retrenchment" from North Carolina's previously generous voting rules. But he also said there was a lack of evidence that the suite of measures – including a voter ID law – actually hurt anybody's access to the franchise.

In fact, minority turnout actually increased in 2014 in North Carolina.

In that way, the judge shed light on the tangled arguments surrounding both sides of the voter ID debate and the still-evolving statistics that underlie them.

The Republican argument that voter ID laws are needed to stem fraud finds very little supporting evidence. Researcher Justin Levitt, in one exhaustive study, found only 31 credible voter impersonation cases out of 1 billion votes cast in the United States.

The fact-checking site Politifact confirmed that cases of in-person voter fraud in Texas – another state with restrictive voting rules – are less common than lightning strikes.

Yet in North Carolina, Democrats, too, struggled to find hard evidence that requiring more proof of eligibility affects the ability to vote – especially since the state allows a person without an ID to vote if they swear to their eligibility in an affidavit.

Nationwide, there is more evidence to support the claim, but the research is not definitive, nor is the effect seen to be as large as the uproar would suggest.

A recent University of California at San Diego study found that, in states with strict voter ID laws, minority participation declined by 7.7 percent since 2008, when compared with minority participation in states with more liberal voting rules. By contrast, Republican turnout declined by 4.6 percent.

The study concluded that voter ID laws “skew democracy in favor of whites and those on the political right,” but it also acknowledges that “Our analysis cannot definitively show a causal connection between voter ID laws and turnout.”

During the 2012 presidential election, Nate Silver of the FiveThirtyEight data journalism site suggested that the laws resulted in a 0.4 to 1.2 percentage point net swing to the Republican candidate in seven states. Though those numbers could be decisive in a close race, Mr. Silver found that it lowered President Obama’s chance of winning only slightly. In Pennsylvania, for example, Mr. Obama’s chance of winning went from 84.2 to 82.6 percent, by his calculations.

'What are they doing wrong?'

For their part, voters – even Democrats – favor voter ID laws, according to a 2012 Pew Research Center study. But the laws’ tendency to rile up the base on both sides is apparent.

“On the Republican side, there’s not much evidence that these laws are needed to prevent people from impersonating someone else and casting a ballot, yet most Americans favor these laws, so it’s something you can do as a Republican that people think is a great thing and it doesn’t cost any money,” says Charles Bullock, a political scientist at the University of Georgia in Athens. “Democrats then take it and say to minority voters, ‘Hey, look, those Republicans are trying to keep you from voting,’ and that encourages them to go to the polls.”

Some Republicans have questioned their own party’s tactic.

“It’s just sad when a political party has so lost faith in its ideas that it’s pouring all of its energy into election mechanics,” former Wisconsin state Sen. Dale Schultz, a Republican, told a radio show in 2014. “We should be pitching as political parties our ideas for improving things in the future rather than mucking around in the mechanics and making it more confrontational … and trying to suppress the vote.”

But without clarity about whether such laws actually do suppress the minority vote to a significant degree, such arguments lose their luster, argues Merle Black, a political scientist at Emory University in Atlanta.

“Maybe it’s not to reduce turnout, maybe it’s to make sure people who are voting are actually eligible to vote – how about that as an explanation?” he says. Voter ID laws, after all, are “pretty popular, so what are [Republicans] doing wrong here politically?”

Even for those who are more skeptical of the laws’ motives, there are questions about how much the laws hurt Democrats or help Republicans.

“Even if this law is passed with discriminatory intent … that doesn’t actually mean that it’s going to have a very significant effect on turnout,” says Professor Greene at North Carolina State. “That doesn’t make [Monday’s ruling] right, but, let’s put it this way: The impact [of the law] is less than the doom-saying prophecies of Democrats, and it’s less than the Republicans who wanted to use it to suppress Democratic minority voters.”