With the decision, Georgia’s counties remain among the 33 percent of counties nationwide that use either machines with no paper trail or machines that print paper ballots that are then scanned on separate machines. The majority of the rest of the counties use paper ballots filled out by hand, which are then scanned or counted by hand. With the passage of the Help America Vote Act in 2002, all polling places nationwide must also include at least one electronic voting machine for voters with disabilities.

Read: The surprising good news about voting security

But with Texas, Ohio, Pennsylvania, Delaware, and New Jersey among the many states also overhauling their election systems before the 2020 presidential election, Georgia’s decision has computer scientists and election experts worried that lessons learned during nearly two decades of computerized voting are being woefully ignored. Indeed, hundreds of millions of dollars have been or will soon be spent in these and other states on technology that experts say decreases election security and erodes election integrity. And this, they say, will only contribute to the sizable portion of the American public that already worries its votes are vulnerable to hacking and other threats.

The sentiments of many computer scientists were crystallized by Richard DeMillo, a colleague of Lee’s at Georgia Tech, who recommends casting paper ballots filled out by hand for all voters, except those with disabilities who would benefit from using machines. “You simply can’t construct a trusted paper trail,” DeMillo says, “if you let a machine make a ballot for you.”

Computer science’s scrutiny of voting systems goes back several decades. The Federal Election Commission issued its first standards for computer-based voting as far back as 1990, but it wasn’t until the 2000 presidential race between George W. Bush and Al Gore, which hinged on the shortcomings of punch-card voting, that states across the nation began to digitize their election systems to varying degrees. Just three years later, one of the first independent computer security analyses of electronic voting systems was already raising flags.

With the global spread of computer technology and the sophisticated tactics of nefarious actors, concerns have only multiplied since then—not least because many state voting systems have not been redesigned since shortly after Bush’s election. Those systems are “vulnerable to nation-states now,” says E. John Sebes, the chief technology officer of the Open Source Election Technology Institute, a nonprofit organization that researches and develops election technology, “and operated by county officials with no IT experience.”

That was among the concerns raised in a 160-page report published last year by the National Academies of Sciences, Engineering, and Medicine. In that report, some of the nation’s leading experts on computer science and elections concluded that there is no “technical mechanism currently available that can ensure that a computer application—such as one used to record or count votes—will produce accurate results.” One reason the authors noted: Malicious software “can be introduced at any point in the electronic path of a vote—from the software behind the vote-casting interface to the software tabulating votes—to prevent a voter’s vote from being recorded as intended.”