- A post-certification signature challenge filed by an individual or private advocacy organization against an election official, arguing that the election official should be ordered to remove a candidate's name or a ballot measure from the ballot, because the election official erred in their determination that sufficient valid signatures were submitted to qualify the candidate or measure for the ballot, or,
- A lawsuit filed by the supporters of a candidate or a ballot measure against an election official, if they believe the election official has improperly refused to certify their candidate or ballot measure for the ballot by failing to count signature as valid that actually are valid.
In either case, the focus of the lawsuits are typically very detailed, signature-specific, arguments as to why a particular signature should either be thrown out or counted.
Signature challenges in 2008
- Colorado Civil Rights Initiative (2008)
- Colorado Right to Work Initiative (2008)
- Florida Hometown Democracy
- Andy Dillon recall (2008)