If the machine mis-records the vote because of error or maliciousness, there’s little chance the mistake will be detected.

An optical-scan machine in Oklahoma Cityduring the 2016 presidential primary. 

CreditCreditBrett Deering/Getty Images

By Kim Zetter  Feb. 21, 2018

In 2011, the election board in Pennsylvania’s Venango County — a largely rural county in the northwest part of the state — asked David A. Eckhardt, a computer science professor at Carnegie Mellon University, to examine its voting systems. In municipal and state primaries that year, a few voters had reported problems with machines ‘‘flipping’’ votes; that is, when these voters touched the screen to choose a candidate, the screen showed a different candidate selected. Errors like this are especially troubling in counties like Venango, which uses touch-screen voting machines that have no backup paper trail; once a voter casts a digital ballot, if the machine mis-records the vote because of error or maliciousness, there’s little chance the mistake will be detected.