The pollbooks must be loaded and tested before the election by members of both parties - Democrats and Republican poll workers. Furthermore, there must be validation of the data entered into those poll books including the list of registered voters. The list of those voters must be verified against external data from Social Security Admin, IRS, death certificates, records of who has moved, etc. That is the only way to ensure that the poll books show an accurate and current list of REGISTERED VOTERS> This testing should be performed by members of BOTH POLITICAL parties to ensure both parties agree it is not a biased process.