Paper Trail Audit

A paper trail audit is a procedure used in elections that rely on electronic voting machines or optical scanners to verify that the digital count matches the physical record of votes cast. The "paper trail" is typically a voter-verified paper audit trail (VVPAT) — either a hand-marked ballot that was scanned, or a printout produced by a direct-recording electronic (DRE) machine that the voter inspects before casting.

After polls close, auditors draw a sample of paper ballots from selected precincts or batches and hand-count them, then compare the result to the machine-reported totals. Discrepancies beyond a small tolerance trigger expanded counting or, in some jurisdictions, a full recount.

Two main methodologies are in widespread use:

• Fixed-percentage audits, which examine a set share of precincts or ballots regardless of margin.
• Risk-limiting audits (RLAs), developed by statistician Philip Stark, which sample ballots until there is strong statistical confidence that the reported winner is correct. The sample size shrinks for landslides and grows for close races.

In the United States, the Help America Vote Act of 2002 accelerated the move toward auditable systems, and by the 2020 general election the large majority of ballots cast nationwide had an associated paper record. Colorado was the first state to require risk-limiting audits statewide, beginning in 2017. Other countries — including Germany, where the Federal Constitutional Court ruled in 2009 that paperless e-voting was unconstitutional — have used the absence or presence of a paper trail as a benchmark for whether electronic systems satisfy transparency requirements.

Paper trail audits are distinct from recounts: a recount re-tabulates all ballots after a contested or close result, while an audit is a routine verification step intended to detect machine error, programming mistakes, or tampering before results are certified. They are considered a core element of election integrity by bodies such as the U.S. Election Assistance Commission and the OSCE/ODIHR.