Like many in his profession, Dr. George Richardson may at times have whisked through his signature in a barely legible fashion. The scrawl had long been sufficient to prescribe medication, but it didn’t pass muster with election judges in Texas, and in 2018, unbeknownst to him, his absentee ballot was disqualified.

That act, an election official eyeballing a signature and summarily rejecting a ballot because it doesn’t appear to match one on file, has become a central point of dispute as political parties jockey in courts around the country for every possible election advantage.

“The record in our case showed that in these election cycles, thousands of votes can be rejected because of perceived disconnects between signatures,” said Richard Mancino, who was one of a team of lawyers representing Richardson in suing the Texas secretary of state for depriving him of his 2018 vote.

“This can affect thousands of voters,” Mancino said. “And in the current circumstances, with the volume of mail-in ballots set to increase substantially, the risk of voters being disenfranchised is substantial.”

How election officials review signatures, and specific rules for potentially rejecting ballots, are questions being tested in dozens of cases around the country.

With a global pandemic still spreading and voters more reluctant to stand in long lines or crowds, election officials are already bracing for 2020 to produce the largest number of absentee and mail-in ballots in U.S. history. And signature matching remains one of the most common techniques used to verify registered voters.

In Jefferson County, Colorado, where elections have been conducted almost entirely through mail-in balloting for the last seven years, officials have developed a protocol for checking signatures that they believe protects both elections and voters’ rights.

“Signature verification is the cornerstone of our security for this model,” said George Stern, Jefferson County’s clerk and recorder. “It has made this one of the safest states in the country to cast a ballot.”

Under Colorado’s rules, bipartisan election judges who have been trained by FBI handwriting experts are charged with reviewing ballot signatures. Stern said suspicious signatures are flagged and put through a second review. If questions remain, the voter is contacted and has a chance to verify their ballot up to eight days after the election.

“Every election we have signatures that do not match,” Stern said.

But the number resulting in fraud is “exceedingly small.” He said one study showed nine instances over seven years where someone other than the voter signed — and that’s out of 16 million votes cast.

“It’s important to get signature verification right in both directions,” Stern said. “We don’t want anyone who should not be voting to send in a ballot. And on the flip side, it’s equally important that we not be rejecting a valid voter because their signature is not perfect.”

But in other parts of the country, the system for checking signatures is not as formalized.

Vanita Gupta is president of The Leadership Conference on Civil and Human Rights, which has been tracking the legal activity on the issue. She said when verification is “done according to best practice” it can be a valuable way to protect elections.

“But to ensure that no voter is unfairly disenfranchised, it’s equally important that voters have an opportunity to address, or cure, any issues with their ballot if officials are not able to verify their signature,” Gupta added.

That is what Mimi Marziani, president of the Texas Civil Rights Project, the organization that helped bring the case on behalf of Richardson and other plaintiffs, said was their concern in Texas.

“We submitted voluminous evidence in this case showing the way the Texas process works now — using non-trained folks to eyeball signatures and giving those people unfettered discretion to throw ballots in the trash,” Marziani said. “That system is both unconstitutional and deeply arbitrary.”

This week, a federal judge on the case ruled in Richardson’s favor, saying the decision to toss his ballot and some 3,700 others in 2018 based on a perceived signature mismatch “plainly violates certain voters’ constitutional rights.” The court said county election judges should either cancel the requirement entirely or make plans to contact voters about questionable signatures and provide them a “meaningful opportunity” to correct any issue before their votes are rejected.

But state officials in Texas immediately moved to appeal. And cases being argued in other states have seen inconsistent outcomes. As Election Day nears, federal judges are rushing to establish clear rules to help avert partisan clashes should officials try to cancel votes because of questionable signatures.

To the Trump campaign, which has been sounding alarms about the potential for people to use mail-in ballots to cast votes illegally, signature matching represents a prudent protection.

“President Trump and his team are fighting for a free, fair, transparent election — and that includes signature-matching requirements so that election officials actually know who is casting ballots,” said Thea McDonald, a campaign spokeswoman. “Verifying a voter’s identity shouldn’t be a political issue, but the Democrats … constantly make it one.”

Last week a federal judge in Tennessee agreed, ruling against a collection of civil rights groups that argued the signature matching requirement “creates a substantial risk that voters will be erroneously denied their fundamental right to vote.” U.S. District Judge Eli Richardson said that while signature verification may present an obstacle, it “does not mean that Plaintiffs are excluded from voting.”

In Pennsylvania, Democrats are in court arguing that signature matching alone “is an inherently flawed means of determining whether a mail-in ballot is fraudulent or improperly cast.” In a case still being litigated, they said no two signatures are ever alike — a different pen or a different writing surface could change the end result.

They allege that a more serious concern is that the requirement to produce an identical signature is unreasonable and unfair to voters with disabilities, the elderly, those with less formal education, or those who more recently learned English. The legal complaint cites a study in Florida that found ballots were more than twice as likely to be rejected on signature discrepancies if the voter was black or Latino. They argue the practice should not alone be enough to disqualify a ballot.

Attorneys for Trump, they “disagree” with any contention the Pennsylvania signature-matching rules are unconstitutional and are asking a federal judge to uphold them.

In Texas, attorneys for Richardson and the other plaintiffs who sued over the state’s signature-matching initiative said they still don’t know what will happen on Election Day.

Marziani said she hopes the recent order requiring more protections for voters will hold up on appeal and be viewed in the context of the national conversation about the importance of election integrity.

“People come at that concept from lots of different viewpoints,” Marziani said. “One common agreement is that we should be accurately counting every eligible ballot. And the state of Texas has unfortunately been trashing thousands of eligible ballots, which really undermines the integrity of our elections. That is something everyone should be concerned about.”