For any voting system to be considered fair and functional, it must be usable by every member of the voting body. In many elections, this could mean any individual of a responsible age, including those who are elderly, disabled, uneducated or unfamiliar with the technology being employed. In most cases, voters should be able to perform this function without requiring training or prolonged instruction, so systems should be self-explanatory and easy to understand. All of these issues are especially relevant in the general field of EVMs, and in particular for open-audit voting systems, where user interfaces are designed around the functionality of several key client-side methods including ballot casting and E2E verification. In this light, any threat against usability must be also seen as a threat to the integrity and functional core of such systems.
In the wake of the 2000 presidential election, the Help America Vote act of 2002 was written into law to update the standards to which voting is held. Among other things, Title III of this act requires voters be allowed to review and correct their ballots, disabled voters be given the same ability to participate, instructions on casting votes remain clear and available, and the voting system allows for auditing.
EVMs are well suited to meet these requirements. They can provide direct feedback to the user as they vote and offer features to visually impared users such as variable font sizes. When properly employed, Research has shown that elections which include electronic voting systems tend to see increases in voter turnout, especially when voting over the internet is allowed (Gibson, 2001). When properly employed, EVMs can improve the accessibility of an election beyond what is possible with just paper ballots.