> While in a conventional election with ballot papers, manipulations or acts of electoral fraud are … only possible with considerable effort and with a very high risk of detection, which has a preventive effect, programming errors in the software or deliberate electoral fraud committed by manipulating the software of electronic voting machines can be recognised only with difficulty. … The voters themselves must be able to understand without detailed knowledge of computer technology whether their votes cast are recorded in an unadulterated manner as the basis of vote counting, or at any rate as the basis of a later recount.
http://electiondefensealliance.org/germany_rules_evoting_unc...
http://history.edri.org/edri-gram/number7.5/no-evoting-germa...