Prior to election certification, the county auditor must conduct a comparison of duplicated ballots to original ballots.  The county auditor must also conduct an additional audit using at least one of the following methods:

• an audit of votes cast on direct recording electronic (DRE) voting devices if more than 10 votes were cast on DRE devices or other in-person ballot marking systems on any race in the county;

• a random check of ballot counting equipment comparing the electronic count of ballots to the machine count from the original ballot counting equipment, which must be conducted if requested by observers from both major political parties;

• a risk-limiting audit, which uses statistical principles and methods to determine, based on a random sampling of paper ballots, whether ballot counting equipment interpreted and tallied the results correctly within an acceptable probability (or risk limit); or

• any independent electronic audit of the original ballot counting equipment using an accurate and independent system approved by the Secretary of State (SOS).

There are two types of risk-limiting audits authorized in statute:

• a ballot comparison risk-limiting audit, in which the county auditor compares the voter markings on the ballot to the ballot-level cast vote record (CVR) produced by the ballot counting equipment until the prespecified risk limit is met; and

• a ballot polling risk-limiting audit, used in counties where the ballot counting equipment does not produce a ballot-level CVR, where the county auditor reports the markings on randomly selected ballots for a selected contest until the prespecified risk limit is met.

Generally, a CVR is an electronic record of a voter's ballot selections formatted in a way that can provide a record of voter selections which can be counted in an efficient manner to produce election results.  A CVR is created by equipment, such as batch-fed optical scanners (i.e. tabulation machines), and then collected by election officials on memory devices and subsequently copied to an election management system that aggregates and tabulates the votes. 

The procedure for postelection audits is modified to remove the option of completing an audit by performing either an audit of DREs, a random check of ballot counting equipment, or an independent electronic audit of the original ballot counting equipment.  Instead, auditors must conduct, in accordance with rules adopted by the SOS, a postelection audit by completing at a minimum a limited hand-count audit of randomly selected precincts or batches of ballots or a risk-limiting audit.

A limited hand-count audit of randomly selected precincts or batches of ballots requires a comparison of a manual count of ballots to the results for the selected precincts or batches recorded by the original ballot counting equipment.  At least one precinct or two batches per ballot scanner must be included in the audit.  The audit is limited to one office or issue which must be randomly selected according to procedures established by the county canvassing board .  The audit must be expanded, according to procedures adopted by the board that are consistent with the rules adopted by the SOS, to include additional ballots when the audit results in an unresolved discrepancy.

A county opting to use risk-limiting audits may choose a third type of risk-limiting audit called the batch comparison risk-limiting audit which involves the selection of random batches of ballots for hand counting for a selected contest until the batch sample meets the prespecified risk limit.  The SOS must adopt procedures for resolving discrepancies between results produced by a ballot counting system and results of a risk-limiting audit and next steps in the case of a failed audit.

When all counties are capable of conducting a ballot comparison risk-limiting audit, the SOS may conduct such an audit on a statewide level on an issue or office that files with the SOS.  Counties may also choose to conduct a risk-limiting audit of a shared district if all counties represented by the district agree to participate.