Most states allow residents to challenge the eligibility of other voters, either before or during an election. Many of these laws originated or were expanded during Reconstruction as a tool for suppressing Black voters. Today, technological advances have made it easy to pull massive amounts of (often unreliable) data from the internet and automatically fill out online voter challenge forms with just a few clicks. Many election deniers, riled up by disinformation about the risk of voter fraud, are doing just that on a mass scale.
Fortunately, federal and state laws protect voters swept up in these challenges. These protections include evidentiary requirements for challenges, prohibitions against frivolous challenges, and constraints on removing voters facing residency-based challenges. The Brennan Center, in partnership with All Voting is Local, has created a set of guides to explain the challenge process, both generally and in 11 battleground states.