Related Rule
Guatemala
Practice Relating to Rule 137. Participation of Child Soldiers in Hostilities
Guatemala’s Law on the Protection of Childhood and Adolescence (2003) states under the heading “Right to Protection during Armed Conflict”: “International humanitarian law. … The State shall adopt all possible measures to ensure that persons below the age of eighteen do not directly participate in hostilities”. 
Guatemala, Law on the Protection of Childhood and Adolescence, 2003, Article 57.