Homeless Ohioans, recently returned veterans, Libertarians, low-income residents who work multiple jobs, and people of color — those are just some of the people who say their civil rights were violated when Ohio’s Board of Elections purged them from the state’s voter rolls.

On Wednesday, the U.S. Supreme Court will hear their case, Husted v. A. Philip Randolph Institute, and consider whether Ohio’s current election rules are fair. If the justices rule in voters’ favor, Ohio will have to go back to the drawing board and find a new way to keep its voter rolls up to date.

Current Ohio voting rules, which have been in place since 1994, flag anyone who fails to vote during a two-year period for potential removal from the rolls of registered voters — even if they’re still technically eligible to vote. Those people are sent a postcard by their local board of elections asking them to confirm their address. If they don’t return the postcard, or fail to vote in a federal election for the next four years, they’re booted off the rolls automatically.

According to Ohio Secretary of State Jon Husted, a Republican, more than 2 million voters were struck from the rolls from 2011 to 2016. Considering that there are approximately 7.7 million eligible voters in Ohio statewide, 2 million is a significant chunk of the electorate.

If the justices rule in Ohio’s favor, that could open the door for other states to implement similar rules.

Voter rolls must be updated periodically to remove people who die or move away. But civil rights advocates and the voters in Husted say Ohio’s election rules are too strict and leave no room for life’s complexities: the transience of an active servicemember’s lifestyle, homelessness, or simply being unable to get to the ballot box due to competing demands of work and family. Or even more basically: someone could forget to return the postcard, or lose the postcard, or it could get lumped in with a neighbor’s mail.

Critics also say that the rules penalize those who simply wish to exercise their right not to vote. According to the United States Election Commission, more than 70 million registered voters didn’t cast a ballot in the 2016 election — approximately a third of all registered voters nationwide.

In September 2016, a federal appeals court in Cincinnati concluded that Ohio’s policy was unlawful because election officials aren’t allowed to penalize people who don’t vote. Ohio argues that the decision to remove someone rests solely on whether they fill out and return the postcard.

The lead plaintiff in the case is the A. Philip Randolph Institute, a black trade unionist organization that describes its mission as advocating for racial equality and economic justice. The group says that Ohio’s voter-roll purges violate two key voting laws: the National Voter Registration Act (NVRA) of 1993 and the Help America Vote Act of 2002.

Husted, who has the backing of the Trump Administration and 17 Republican state attorneys general, says that the current system ensures that voting rolls are up to date and that they comply with federal law.

The case comes as Republicans and Democrats butt heads over voting rights across the country. Some Republican lawmakers insist that the electoral system is plagued by voter fraud. Elections experts say there is no evidence to support the notion of rampant voter fraud, and Democrats say that Republicans are using the myth as an excuse to consolidate power by restricting the voting rights of low-income and minority voters.

There’s data to support the idea that penalizing those who don’t vote would ultimately affect low-income and minority citizens the most. According to the U.S. Census, poor people were much less likely to vote than their wealthy counterparts. Less than half of eligible adults with family incomes under $20,000 voted in 2012, compared to 80 percent of those with family incomes of $100,000 or more.

A Reuters analysis of voter lists in Ohio found that although people of all political leanings were affected by the state’s rules, those most affected lived in largely Democratic neighborhoods in the state’s three largest counties (which encompass Cleveland, Columbus, and Cincinnati). According to the news agency, people in those neighborhoods were purged from rolls at twice the rate of those from mostly Republican neighborhoods.

What’s more, there was often an economic and racial divide. Reuters found that about 10 percent of registered voters near downtown Cincinnati, which has a large black population, had been removed from the rolls since 2012, compared to 4 percent in a white, largely Republican suburb.

In August, the Justice Department abruptly switched sides in the case, revoking an Obama-era brief supporting purged voters and instead throwing its weight behind the state of Ohio. That reversal came about six months after the DOJ switched sides in another landmark voting rights case in Texas. Central to both reversals was John Gore, a Republican attorney who is temporarily overseeing the agency’s Civil Rights Division. Prior to coming to work for the Trump administration, he made a career out of defending restrictive voting policies.

Justin Levitt, an elections expert and law professor at Loyola Law School in Los Angeles who helped write the Obama-era brief siding with voters, says this isn’t a fight over whether voter rolls should be properly maintained — it’s a fight over how they should be maintained in order to ensure their accuracy.

“List maintenance is like surgery,” Levitt said. “It can be really important for the health of the patient, but you gotta do it well, and you gotta do it right. If you do it sloppily, it can do more harm than good.”

The justices are expected to rule in May. It takes four justices to agree to take a case, and given that lower federal appeals courts basically agreed that Ohio was in the wrong, experts have speculated that the four justices who accepted the state’s petition are sympathetic to its argument.