A juvenile is precluded from seeking to attack the legality of a deferred disposition, including a final disposition, except that a juvenile who has been determined by a court to have inexcusably failed to comply with a court-imposed deferment requirement and thereafter has had imposed a dispositional alternative authorized for the juvenile crime may appeal to the Supreme Judicial 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.   [PL 2015, c. 409, §7 (AMD).]