It occurs when a non-governmental organization, such as a political party or a campaign, sends first-class mail to registered voters, in order to compile a so-called "challenge list" of the names of those whose letters are returned undelivered.
The fact that the mail was returned as undeliverable may be seen as either proof, or strong evidence of, the person no longer residing at the address on their voter registration.
In the United States, official government election offices are required to periodically maintain and update their lists of registered voters.
Organizations such as the American Civil Liberties Union and Fair Fight Action periodically take to the courts to challenge the methods used by official government election offices to maintain their lists.
[3] The so-called "caging list" that is the compiled names of all those for whom the envelopes were returned, marked undeliverable, can then be presented by the political party or campaign to election officials, with a request that the election officials should proceed to purge those people from the list of registered voters, or at a minimum, take a second look at whether the voter still resides at the address of registration.
[1] Actions of the Ballot Security Task Force in New Jersey in 1981 are believed to be the first wide-scale use of voter caging as a campaign tactic.
Believing that these tactics violated the Voting Rights Act, the Democratic National Committee took the RNC to federal court.
Rather than see the case fully litigated, the RNC entered a consent decree, which prohibited the party from engaging in anti-fraud initiatives that targeted minorities from conducting mail campaigns to "compile voter challenge lists".
Shortly before the 2004 election, Palast also obtained a caging list for Jacksonville, Florida, which contained many blacks and registered Democrats.
When 35,000 letters were returned as undeliverable, the party employed poll watchers to challenge the voters' right to vote.
"[11] Republicans sent out fundraising mailers to voters in five Florida counties: Duval, Hillsborough, Collier, Miami-Dade and Escambia, with 'do not forward' on the letters.
[17] In the years since the original 1982 consent decree on voter caging, a series of suits and countersuits between the RNC and the DNC as well as civil rights groups and labor unions ensued.
[21] Harvard Law Professor Nicholas Stephanopoulos suggested this decision was at least partially influenced by a general decline in the willingness of courts to intervene in election law issues, as witnessed by several moderately recent decisions by the Supreme Court of the United States, especially in Shelby County v.