What you need to know about vote-by-mail

Officials in Michigan, Nevada, California, New Hampshire and Wisconsin have all recently moved to make it easier for more voters to cast their ballots by mail ahead of the November election.

The Texas Supreme Court, however, blocked a push to expand vote-by-mail to registered voters in the state this week, saying that a lack of immunity to the coronavirus does not count as a "disability" for which a voter can apply for a mail-in ballot.

In both 2016 and 2018, approximately 25% of US voters cast ballots by mail, which includes the handful of states that conduct elections entirely by mail and traditional absentee ballots.

According to the National Conference of State Legislatures, absentee or mailed ballots in several ways "are as secure or more secure than traditional methods of voting." One reason? In most states, these ballots are examined and processed in advance of Election Day, spreading out the workload and allowing more time for scrutiny.

CNN spoke with Rick Hasen, a University of California, Irvine, professor and one of the nation's top experts in election law, about Trump's claims and what they mean for the 2020 election.

The conversation, conducted over the phone and lightly edited for flow, is below.

CNN: I wanted to start with the President. He tweeted that there's "no way that mail-in ballots will be anything less than substantially fraudulent" and he said that the upcoming election will be "rigged."

RH: I'm very concerned that the President is continuing to make wholly unsubstantiated claims of massive voter fraud. He has now shifted his attention to mail-in balloting, which may be the only way that many voters can vote safely under pandemic conditions.

It's not new for the President to make unsubstantiated claims of voter fraud, he made the outlandish claim in 2016 that there were 3 to 5 million noncitizen voters voting in the election, all for his opponent, Hillary Clinton. And now that the pandemic is forcing more people to vote by mail, a form of voting that the President uses himself, he has attacked this process and in a substantial way is undermining his supporters' confidence in the fairness and legitimacy of the 2020 elections.

CNN: Can you walk us through how mail-in voting works and why widespread fraud doesn't occur the way the President's claiming it does?

RH: Sure. Every state has their own rules for how mail-in balloting is conducted. Some states, for example, vote almost exclusively by mail, including the Republican-dominated state of Utah. In many other states, one can vote by mail without an excuse, and in about a third of the states, one needs to present a valid excuse in order to be able to vote by mail. In all of these places, there are safeguards put in place to assure that mail-in voting is conducted fairly.

For example, states require some form of verifying the identity of the voter such as matching signatures. Many states also provide for the ability to track one's ballot to make sure that a ballot has arrived at a voter's home and has been returned to election officials. Many states also give voters the ability to fix or cure a deficiency in absentee ballot when, for example, a signature might be flagged as not matching.

In the rare instances in which someone attempts to tamper with ballots, that kind of conduct is often caught. We saw that in the 2018 US congressional race for North Carolina's 9th Congressional District.

While no voting system is perfect and perfectly free from fraud, the amount of fraud related to absentee balloting is quite low relative to the number of ballots that are cast, and the benefits of absentee balloting, which is primarily convenience for voters and election administrators [which] is now heightened under pandemic conditions where people without immunity to Covid-19 could contract the virus if they need to stand in long lines at polling places under pandemic conditions.

CNN: There's been a narrative linking vote-by-mail to fraud or just promoting the idea of voter fraud, even before Trump entered politics or won the presidency. Why do you think that's the case?

RH: I think that's a complicated question. I address this issue in my new book, "Election Meltdown." I think the key point is that some Republican political operatives have seen it politically advantageous to raise claims that Democrats commit voter fraud for a few reasons.

No. 1, it serves as the predicate for passing laws that make it harder to register and vote, which some Republicans believe is in their electoral self-interest.

No. 2, it provides a basis for casting doubt on legitimacy of the elections when Democrats are elected to office. The claim, which is accepted by some Republican voters hearing these claims of voter fraud, is that these elections are not wholly legitimate.

CNN: So it's politically advantageous?

RH: It's perceived as politically advantageous. I'm actually quite skeptical that an attack by vote-by-mail in particular is going to be helpful to President Trump and Republicans. As we saw in the April 7 Wisconsin primary, these kinds of attempts to claim voter fraud and to cast doubts on voting by mail can backfire on Republicans. In that race, Democrats organized efforts to help voters safely and correctly vote through the use of the mail while the Republican Party did that less and many of their voters suffered.

Similarly, there's reason to believe that smaller rural counties are going to have a harder time ramping up for a largely vote-by-mail election in November should that be necessary. And this may hurt Republican electoral prospects. If the President tells his reliable voters that vote-by-mail is not secure and if voting in person is not considered safe to these voters, then there's the real risk that Republican voter turnout could be depressed by these messages from the President.

CNN: Is there an effective way to combat misinformation about mail voting?

RH: Well, I've been working with a bipartisan group of scholars and others to try to get the word out. We issued a report called "Fair Elections During the Crisis." You can Google those words and find a link to the report in which we talk about the ways in which election administrators, government officials, media companies like CNN and social media companies like Twitter and Facebook can take steps to assure the fairness and legitimacy of the election process, as well as voters' confidence in that process.

Among the steps that we suggest that media companies like CNN take is to explain to viewers that the expected flood of absentee ballots in November that will be caused by reactions to the pandemic is likely to lead to a delay in the full counting of ballots. In places like Michigan and Pennsylvania, they've only recently moved to no-excuse absentee balloting. And so it may be days before we know the winner of the presidential election in those key battleground states if the election is close, and during that period of time, there's the potential that the President could claim victory if he's ahead in the early counts. It's important for decision desks and TV networks to understand the importance of explaining to viewers that races may simply be too early to call, and that a delay in election results is an indication of simply the fact that fair counting takes time and not evidence of foul play.

CNN: Do you worry that statements like this coming from the Oval Office are going to have a long-term negative effect on not just mail-in voting but our democratic system?

RH: I think a lot depends on how the 2020 election goes and how close it is. If these issues come to the fore and people become more polarized and start believing false claims about massive voter fraud, then I think our very democratic republic is in danger.

This was one of the reasons for my call to create this committee to try to think about how we can bolster the legitimacy and public confidence in the process as much as possible, which is quite difficult to do when you are facing the President of the United States constantly making unsubstantiated claims of voter fraud.