Risk-Limiting Audits with Arlo

Democracy depends upon trust in the electoral process. In the United States, nearly every jurisdiction relies on machines to tally votes, so trusting the process means trusting the machines that scan and tally our paper ballots. Given the high stakes of our elections, and our adversaries’ demonstrated interest in them, what can we do to double-check the equipment producing the tallies?

The best safeguard we have against hacked or otherwise faulty voting systems is a Risk-Limiting Audit (RLA). Experts believe that RLAs are the most efficient way to gain certainty that the winner reported by the voting system is correct.

The RLA is efficient because of its insight that we do not need to manually recount every vote to gain certainty in the outcome of an election. Instead, the number of votes we need to manually count depends on the margin of victory in the contest we’re auditing. A typical state-wide RLA might require checking fewer than 1000 ballots to validate an entire state’s election results.

The code for Arlo is open-source and freely available for anyone to use and host.

Arlo Hosting, Pilots, and Services

VotingWorks provides the following services for Arlo:


We’ve built a collection of short RLA training videos to help everyone on your team to run RLAs with Arlo.

You can also find more resources about Risk-Limiting Audits and a discussion board at RiskLimitingAudits.org.

Email us with your questions: rla@voting.works