Under state law, the Montana Motor Vehicle Division can refuse to issue any license plate containing “any combination of letters or numbers, or both, that may carry connotations offensive to good taste and decency or which are misleading or a duplication of license plates provided elsewhere.”
To help the government do its job regulating license plates, the MVD maintains a list of 4,212 plates that are banned from circulation. Most banned plates clearly deserve to be on the list. For others, the reason why they aren't allowed is far less clear.
Here are 17 apparently normal license plates that Montana has forbidden.