Mass. Gen. Laws ch. 120 § 17
Whenever the department is of the opinion that discharge of a person from its control at the age limit stated in section sixteen would be physically dangerous to the public, the department shall make an order directing that the person remain subject to its control beyond the period and shall make application to the committing court for a review of that order by the court. The order and application may be made at any time prior to the date of discharge stated in said section sixteen. The application shall be accompanied by a written statement of the facts upon which the department bases its opinion that discharge from its control at the time stated would be physically dangerous to the public, but no such application shall be dismissed nor shall the order be discharged, merely because of its form or an asserted insufficiency of its allegations; every order shall be reviewed upon its merits.
Mass. Gen. Laws ch. 120, § 17