A letter of pardon is a letter of recommendation in support of a person's pardon or a letter specifically from the person requesting the pardon. The letter is typically written to the state governor or a judge.
A letter of pardon includes the letter writer's relationship to the person requesting pardon and the reasons why the pardon is necessary. For example, the letter should detail how the person has reformed himself, made amends for his mistakes and shown a change in character. In addition, a letter of pardon may offer proof of a person's innocence and a plea to reconsider a judicial decision.