Me. Rev. Stat. tit. 17-A, § 1904

A person may not attack the legality of a deferred disposition, including a final disposition, except that a person who has been determined by a court to have inexcusably failed to comply with a court-imposed deferment requirement and thereafter has been sentenced to an alternative authorized for the crime may appeal to the Law Court, but not as of right. The time for taking the appeal and the manner and any conditions for the taking of the appeal are as the Supreme Judicial Court provides by rule.