How common is voter fraud, and what do the studies actually measure?

Studies of US elections have generally found voter fraud to be rare, though people disagree about what that implies for the rules. Electoral fraud, or voter fraud, is illegal interference with an election, either by raising a favoured candidate's share, lowering rivals' shares, or both. In a narrow election, a small amount could change the result, and even a revelation that does not can reduce voters' confidence in democracy.

The numbers come from different studies that count different things. In 2017 the Brennan Center pointed to its review of elections that had been meticulously studied for fraud, which found voter impersonation incident rates of 0.0003–0.0025%. North Carolina's Board of Elections reported that, out of 4,769,640 votes cast in November 2016, only one illegal vote would potentially have been blocked by the state's voter ID law, and found fewer than 500 invalid ballots, mostly cast by people on felony probation who were likely unaware they could not vote. An April 2020 MIT study of 20 years found mail-in ballot fraud "exceedingly rare", at "0.00006 percent" of instances nationally. One count found 491 absentee-ballot fraud cases between 2000 and 2012, out of billions of votes.

Not everyone draws the same policy conclusion. Supporters of voter ID laws argue that voter impersonation can be hard to detect without them. The effectiveness of those laws given the rarity of impersonation, and their potential to disenfranchise citizens without the right ID, have created controversy.

Fraud is not imaginary everywhere. Malawi's Constitutional Court nullified the 2019 general election in 2020 because many results were changed using correction fluid and results forms were duplicate, unverified or unsigned.