Ballot pseudo-secrecy
One of the things that makes elections so difficult - besides the ridiculousness here in the U.S. of voting on all local, state and federal elections on the same ballot - is the requirement of absolute ballot secrecy.
Doug Jones, in his October 2004 CACM piece, Auditing Elections, points out that the UK does things differently. In the UK, there is, what I call, ballot pseudo-secrecy instead of absolute secrecy ("Procedures at a General Election"):
11.16 The system used to issue ballot papers was introduced in the Secret Ballot Act 1872. Each ballot paper has a number on the back (the front has names and details of candidates as shown in statement of persons nominated) and a corresponding number on the counterfoil. Acting returning officers arrange for ballot papers to be printed locally.
11.17 When the voter presents himself or herself at the polling station, the presiding officer checks that the name is on the register, marks it off and tears off the ballot paper. The polling clerk writes the voter's electoral number on the counterfoil. A perforation (the "official mark") which identifies the polling station is made on the ballot paper and the polling clerk gives it to the voter, who makes a mark on it in the polling booth. If the official mark is not present on the ballot paper when the ballot papers are counted, that ballot paper will be regarded as invalid and not counted.
11.18 This procedure ensures that only an elector whose name is on the register votes, and that he or she only votes once. The numbering is necessary so that the presiding officer can account for the number of ballot papers with which they were issued at the beginning of the poll.
Paper ballots are numbered and each number is recorded in a register. As we've shown before (PDF), this kind of thing can violate ballot secrecy and introduce undue influence on voting (coercion, vote-buying, etc.). However, the register is kept and treated as a state secret and primarily used to ensure that all ballots are accounted for - or don't end up in the final tally.
I think that relaxing the requirement for absolute ballot secrecy may be a wise step in the U.S. The machines we use have been shown to work well at times, and to really screw up at other times - with some problems being recoverable and other ones not. If we could use pseudonymous unique identifiers to track votes during the various levels of the canvass, we could approach the end-to-end auditability Doug Jones speaks of.
The trick is that the unique identifier need be unknown to the voter and the "register" that links individuals to unique ID numbers must be kept highly secret.