# Logic and Accuracy Testing **Logic and accuracy testing (L&A)** is the pre-election procedure in which a **test deck** of ballots with a known result is run through each tabulator, and the output is compared with what it should be. The machine is then sealed until election day. Many jurisdictions repeat the test after the count. L&A is the only point before an election at which anyone checks that the count will come out right. It is governed entirely by state law and county procedure manuals. No federal statute requires it, sets the size or makeup of the test deck, or says who may watch. ## What the states require A 2022 fifty-state review (Walker et al., a single academic source) found: | Requirement | States | |---|---| | Pre-election L&A of some kind | all 50 | | At least some testing in public | at least 45 (7 restrict who may attend) | | Every machine tested in public | at least 32 | | All equipment tested, not a sample | at least 44 (Tennessee, Texas and Indiana sample) | | Every ballot style tested | at least 32 | | No public L&A | Kentucky, Maryland, Hawaii | ## How a test deck is built Georgia's manual (Kennesaw State, v1.4, 2015) gives the standard design. The deck mixes blank ballots, fully voted ballots and specifically voted ballots, so that "every candidate in every race receives at least one test vote." It includes deliberate overvotes to confirm the scanner rejects them. The public must get at least five days' notice of the test. The weak spot is a deck in which every choice gets the **same** number of votes. A swap between two candidates, or between yes and no, then produces the right totals, and the test passes. ## What L&A misses, and what it catches - **Missed: Northampton County, Pa., November 7, 2023.** An [[Election Systems & Software]] coding error swapped "yes" and "no" between two judicial-retention questions on the ExpressVote XL printouts, so voters saw the wrong text on their paper. The electronic tally was correct. The county had run only the vendor's automated L&A, with no split votes, which could not show a swap. The state's fixes were manual L&A and an ES&S check of the master ballot against the printouts. - **Caught: Long Beach, Calif., 2014.** Testing a week before the primary found software that failed to read page two of the ballot in 169 of 295 precincts (one source). ## Observers Public L&A is one of the few stages of election administration routinely open to observers, and the one where an outsider can watch the machine prove its own count. Whether anyone may watch, how much notice they get, and how close they may stand are all state law. In the seven states that restrict attendance, and the three with no public test at all, the step happens out of view. ## See Also - [[How a Ballot Is Counted]] · [[How a Voting System Is Certified and Decertified]] - [[Election Management System]]: L&A tests the programming files the EMS builds - [[Optical Scan Voting System]] · [[Ballot Marking Device]] - [[Chain of Custody]] · [[Election Ballot Chain of Custody Flow]] · [[Post-Election Audit Crosswalk]] - [[How Election Results Are Transmitted and Reported]]