Abstract: A voting unit and a ballot transaction processing system for processing a voting session. The voting unit includes an optical ballot scanner and a printer that is capable of printing a non-human readable barcode on ballots that are fed into the voting unit. The ballots are filled out (or cast) by the voter before being inserted into the voting unit. The voter can confirm the voting unit's interpretations of his/her selections on the scanned ballot via a display and confirm that the interpretations are correct via an input section on the voting unit. The ballot transaction processing system is also capable of generating, assigning and communicating to a plurality of voting units a set of unique transaction codes. In so doing, the ballot transaction processing system maintains voter secrecy, prevents ballot stuffing and provides a one-to-one correspondence between images of optically scanned ballots and the ballots themselves.