Paper ballots that can be tallied by hand are the most secure way to conduct an election, according to a report from the US National Academies of Sciences, Engineering, and Medicine.

The report, released on 6 September, calls for all US elections to be conducted using such ballots by the 2020 presidential election. It comes after US intelligence agencies concluded that the Russian government backed attempts to infiltrate the United States’ election infrastructure during the 2016 presidential election. The report's recommendations were developed by a committee with experience ranging from computer science to officiating elections.

“The future of voting is one in which a clear tension must be managed,” wrote committee co-chairs Lee Bollinger, president of Columbia University in New York City, and Michael McRobbie, president of Indiana University in Bloomington. “We must prevent bad actors from corrupting our electoral process while delivering the means to provide suffrage to an electorate that is growing in size and complexity.”

For now, that means eschewing voting systems connected to the Internet until “robust guarantees of security and verifiability” are in place, the committee concluded.

The report says it is safe for paper ballots to be counted by a machine using an optical scanner, but it stipulates that recounts and audits should be conducted by hand. It also recommends the immediate removal of voting machines that do not allow manual auditing.