July 12, 2021
Election Administration: An Introduction to Risk-Limiting
Audits
Election officials conduct checks throughout the election
Risk-limiting audit procedures themselves start with
cycle. They set up controls to guard against unauthorized
selection of an initial random sample of paper records,
access to voter registration rolls, for example, and to help
based on factors such as margin of victory. Those paper
ensure that poll workers follow the correct procedures.
records are manually reviewed to check for any
discrepancies with voting system outputs. Statistical
Some election checks focus on the vote counting stage of
calculations are then run on the results to determine
the process. They aim to ensure that the equipment and
whether they provide a prespecified level of confidence—
procedures used to capture and count votes report the right
which might be set in statute or chosen by election
election outcomes.
officials—that the election outcomes reported by the voting
system are the outcomes officials would get if they
One tool officials can use to help check the accuracy of
conducted a full hand count of the paper records of votes.
election outcomes is a type of post-election audit known as
a risk -limiting audit. Risk-limiting audits have been
If the prespecified confidence threshold is met, the audit
recommended as an election security measure by the Senate
can stop there. If not, the size of the sample is increased
Select Committee on Intelligence and the National
until either the threshold is met or all of the paper records
Academies of Sciences, Engineering, and Medicine, among
have been manually reviewed. The election outcomes
others, and are the subject of ongoing activity at both the
revealed by the full hand count would stand in the latter
state and federal levels.
case, if the reported and hand-counted outcomes were to
differ.
Overview
Vote counting is compiling individual voters’ selections to
Paired with a trustworthy paper trail, risk-limiting audits are
reveal election outcomes. A basic expectation is that the
designed to provide either (a) a quantifiable level of
equipment and procedures used to conduct the count will
confidence that the election outcomes reported by the
get those outcomes right, reporting the candidates voters
voting system are right or (b) a way to correct the reported
chose for the seats as the winners of elections.
outcomes—through a full hand count—if they are wrong.
Traditional post-election audits that review a fixed share of
Election officials can take steps to help ensure that vote
paper records, by contrast, might review too few records to
counting systems perform as expected. One available
provide confidence in the reported outcomes, and
approach is to try to prevent any issues that could affect
preventative measures might not catch all potential issues.
reported outcomes. Running test decks of ballots through
ballot scanners before the polls open—as part of a pre-
Other possible benefits have also been claimed for risk-
election logic and accuracy test—can help flag potential
limiting audits, including potential to reduce audit costs,
scanner configuration issues, for example. Testing and
increase voter confidence, deter fraud attempts and
certification programs can help ensure that voting systems
unnecessary recounts, and simplify other election processes.
meet specified security and reliability guidelines.
Election officials might be able to scale back some
preventative voting system testing and certification
Another, complementary approach is to identify any issues
processes, for example, if they have a way to identify and
after the fact and, if necessary, recover from them. One
correct for vote counting issues after the fact.
general strategy for this approach—of which risk-limiting
audits are an example—is to compare the election outcomes
Risk-limiting audits may also come with challenges. Some
reported by the voting system to paper records of votes that
state and local officials have expressed uncertainty about
voters have had a chance to verify.
how to implement risk-limiting audit procedures, for
example, or concerns about the accessibility of paper-based
A prerequisite for an effective risk-limiting audit is a
voting systems and vote verification mechanisms to
trustworthy paper trail, to ensure that reported outcomes are
individuals with disabilities.
checked against paper records that accurately reflect voters’
selections. A full discussion of how to secure the paper trail
Costs may be a concern for some jurisdictions as well.
is beyond the scope of this In Focus, but some of the
Risk-limiting audits may be more cost-effective than
procedures involved include efforts to ensure that voters
traditional post-election audits in general. Because they can
generally do tend to verify the paper records of their votes
escalate beyond initial samples, however, they are more
and that no paper records are added, changed, or removed
expensive in certain cases and can introduce an element of
after voters have had a chance to verify them.
uncertainty about funding needs. Risk-limiting audits may
also represent new expenses for states and localities that do
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link to page 2 link to page 2 link to page 1 Election Administration: An Introduction to Risk-Limiting Audits
not currently conduct traditional post-election audits or that
Virginia had enacted laws requiring risk-limiting audits,
would have to acquire new equipment or develop new
and California, Ohio, Oregon, and Washington had statutes
procedures to support risk-limiting audits.
or administrative directives permitting them.
Federal Activity
Other jurisdictions have taken preliminary action on risk-
Federal election law does not specifically address risk-
limiting audits. A number of states—including Georgia,
limiting audits. The Help America Vote Act of 2002
Indiana, Michigan, New Jersey, and Pennsylvania—have
(HAVA; P.L. 107-252; 52 U.S.C. §§20901-21145) requires
conducted risk-limiting audit pilot programs. Some of those
voting systems used in federal elections to produce
and other states and localities have also used the federal
manually auditable permanent paper records. HAVA has
funds described in the “Federal Activity” section of this In
not been interpreted as mandating the individual, voter-
Focus to research, develop, or pilot risk-limiting audits.
verified paper records used in risk-limiting audits, though,
Congressional Proposals
and it requires only that records are auditable, not actually
As noted in the “State Activity” section of this In Focus,
audited.
many states and localities have started exploring or
implementing risk-limiting audits. Congress might choose
The federal government has taken other steps to facilitate
to leave any decisions about further action on risk-limiting
development or implementation of risk-limiting audits,
audits to state and local officials.
however. First, Congress has provided funding that could
be used for work on risk-limiting audits. Appropriations for
Bills have also been introduced that would assign the
FY2009 and FY2010, for example, included funding
federal government a role. Some of this legislation would
specifically for a state and local pre-election logic and
provide federal support for state and local action. That
accuracy testing and post-election audit grant program.
includes support for state and local decisionmaking, such as
More recent federal funding—appropriated for FY2018 and
research into the feasibility or effects of conducting risk-
FY2020 in response to election security concerns—was
limiting audits.
available to states for general improvements to the
administration of federal elections, including
It also includes help addressing challenges like the ones
implementation of post-election audits.
described in the “Overview” section of this In Focus. Bills
have been introduced to provide technical assistance with
States and localities have used some of those federal funds
conducting risk-limiting audits, for example, and to
to develop or implement risk-limiting audits. California,
authorize grant programs for conducting risk-limiting audits
Colorado, and Cuyahoga County, Ohio, used the earlier
or developing accessible paper ballot verification methods.
funding to pilot or document risk-limiting audit procedures,
for example, and the U.S. Election Assistance Commission
Other risk-limiting audit-related legislation would mandate
(EAC) has described work on risk-limiting audits as a
common theme of states’ proposed spending of more recent
state or local action. Proposals have been offered to require
states to conduct risk-limiting audits for federal elections,
funds.
for example, and to require voting systems used in federal
elections to produce voter-verified paper records.
Second, federal agencies have offered nonfinancial support.
The U.S. Department of Homeland Security’s
Many risk-limiting audit-related provisions have appeared
Cybersecurity and Infrastructure Security Agency (CISA)
in multiple bills across multiple Congresses. Risk-limiting
partnered with a nonprofit organization to develop a risk-
audit requirements have appeared in the Protecting
limiting audit tool, for example, and the National Institute
American Voters and Elections (PAVE) Act of 2018 (H.R.
of Standards and Technology (NIST) has specified an audit-
6093/S. 3049) and 2019 (H.R. 2754/S. 1472) and the 116th
friendly common data format for a type of information
Congress’s Securing America’s Federal Elections (SAFE)
often used in risk-limiting audits.
Act (H.R. 2722/S. 2053/S. 2238), for example. The For the
People Act of 2019 (H.R. 1/S. 949) and 2021 (H.R. 1/S. 1)
The EAC included support for that common data format, as
and the 116th Congress’s Heroes Act (H.R. 925/H.R.
well as for risk-limiting audits, among the requirements
6800/H.R. 8406/S. 4800), among others, have proposed
voting systems must meet to receive certification under the
grant programs for conducting risk-limiting audits.
newest version of its Voluntary Voting System Guidelines
(VVSG 2.0). The agency has also produced audit-related
None of the bills referenced above has been enacted as of
resources for states and localities—including a white paper
this writing, but some have passed the House. The Election
on risk-limiting audits and a more general publication on
Technology Research Act of 2020 (H.R. 4990), which
post-election audits—and provided states with risk-limiting
would have directed NIST to provide technical assistance
audit trainings and technical assistance.
with risk-limiting audits, was passed by the House. The
State Activity
House has also passed versions of the For the People Act of
2019 (H.R. 1) and 2021 (H.R. 1), the Heroes Act (H.R.
Starting with Colorado, which enacted the first risk-limiting
925/H.R. 6800), and the SAFE Act (H.R. 2722).
audit statute in 2009 and conducted the first statewide risk-
limiting audit in 2017, some states have adopted risk-
limiting audit policies. According to the National
Karen L. Shanton, Analyst in American National
Conference of State Legislatures, as of January 2021,
Government
Colorado, Nevada (effective 2022), Rhode Island, and
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Election Administration: An Introduction to Risk-Limiting Audits


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