This article was originally posted at Freedom to Tinker on October 16, 2018.
The Dominion ImageCast Evolution looks like a pretty good voting machine, but it has a serious design flaw: after you mark your ballot, after you review your ballot, the voting machine can print more votes on it!. Fortunately, this design flaw has been patented by a rival company, ES&S, which sued to prevent Dominion from selling this bad design. Unfortunately, that means ES&S can still sell machines (such as their ExpressVote all-in-one) incorporating this design mistake.
When we use computers to count votes, it’s impossible to absolutely prevent a hacker from replacing the computer’s software with a vote-stealing program that deliberately miscounts the vote. Therefore (in almost all the states) we vote on paper ballots. We count the votes with optical scanners (which are very accurate when they haven’t been hacked), and to detect and correct possible fraud-by-hacking, we recount the paper ballots by hand. (This can be a full recount, or a risk-limiting audit, an inspection of a randomly selected sample of the ballots.)
Some voters are unable to mark their ballots by hand–they may have a visual impairment (they can’t see the ballot) or a motor disability (they can’t physically handle the paper). Ballot-marking devices (BMDs) are provided for those voters (and for any other voters that wish to use them); the BMDs are equipped with touchscreens, and also with audio and tactile interfaces (headphones and distinctively shaped buttons) for blind voters, and even sip-and-puff input devices for motor-impaired voters. These BMDs print out a paper ballot that can be scanned by the optical scanners and can be recounted by hand.