Mass. Gen. Laws ch. 119, § 86
(a) For the purposes of this section, the following words shall, unless the context clearly requires otherwise, have the following meanings:—
''Juvenile'', (1) a person appearing before a division of the juvenile court department who is (i) subject to a delinquency proceeding, (ii) a child requiring assistance or (iii) a child in a care and protection proceeding or (2) a person under the age of 21 in a youthful offender proceeding.
''Restraints'', a device that limits voluntary physical movement of an individual, including leg irons and shackles, which have been approved by the trial court department.
(c) The court officer charged with custody of a juvenile shall report any security concern to the presiding justice. On the issue of courtroom or courthouse security, the presiding justice may receive information from the court officer charged with custody of a juvenile, a probation officer or any other source determined by the court to be credible.
The authority to use restraints shall reside solely within the discretion of the presiding justice at the time that a juvenile appears before the court. A juvenile court justice shall not impose a blanket policy to maintain restraints on all juveniles or a specific category of juveniles who appear before the court.