Practice Relating to Rule 137. Participation of Child Soldiers in Hostilities
Uruguay’s Law on Cooperation with the ICC (2006) states:
26.2. Persons and objects affected by the war crimes set out in the present provision are persons and objects which international law protects in international or internal armed conflict.
26.3. The following are war crimes:
34. … using [children under the age of eighteen years] to participate actively in hostilities.
Upon ratification of the 1989 Convention on the Rights of the Child, Uruguay stated that “it will not authorize any persons under its jurisdiction who have not attained the age of 18 years to take a direct part in hostilities”.
At the 27th International Conference of the Red Cross and Red Crescent in 1999, Uruguay pledged “to promote the adoption of national and international standards prohibiting the military … participation in armed conflicts of persons under 18 years of age”.
In 2003, in its second periodic report to the Committee on the Rights of the Child, Uruguay stated: “Article 13 of the new children’s code specifically provides that children and young people cannot participate in hostilities in armed conflicts or be trained for that purpose.”
In 2012, in its initial report to the Committee on the Rights of the Child under the 2000 Optional Protocol on the Involvement of Children in Armed Conflict, Uruguay stated:
10. The provisions applicable for the purpose of preventing the deployment of minors under the age of 18 years in conflict zones include the rules contained in article 77.2 (Protection of Children) of [the 1977] Protocol I Additional to the Geneva Conventions of 199, approved by Act No. 15764 of 13 September 1985, whereby it is established that the parties to the conflict shall take all feasible measures to ensure that children under the age of 15 do not take a direct part in hostilities and are not recruited into the armed forces.
11. At the time it deposited its instrument of ratification of the  Convention on the Rights of the Child, the Eastern Republic of Uruguay declared “ … in regard to the provisions of article 38, paragraphs 2 [according to which States Parties have to take all feasible measures to ensure that children under 15 years of age do not take direct part in hostilities] and 3 [according to which States Parties shall refrain from recruiting persons under 15 years of age], that in accordance with Uruguayan law it would have been desirable for the lower age limit for taking a direct part in hostilities in the event of an armed conflict to be set at 18 years instead of 15 years as provided in the Convention. Furthermore, the Government of Uruguay declares that, in the exercise of its sovereign will, it will not authorize any persons under its jurisdiction who have not attained the age of 18 years to take a direct part in hostilities and will not under any circumstances recruit persons who have not attained the age of 18 years.”
12. In addition, the binding declaration made in accordance with article 3, paragraph 2, of the  Optional Protocol [on the Involvement of Children in Armed Conflict] establishes that: “in the exercise of its sovereign will and in accordance with Uruguayan law, it will not under any circumstances permit voluntary recruitment into its national armed forces of persons who have not attained the age of 18 years”.
13. It is worth noting that there was consensus in the political and social circles of the country with respect to the content of this declaration.
14. This position is reflected in the clause in the Code on Children and Adolescents, Act No. 17823 of 7 September 2004 (see annex II), according to which children and adolescents cannot take part in hostilities in armed conflicts or receive preparation for that purpose.
17. The Armed Forces of Uruguay take part in United Nations peacekeeping missions, to which no personnel under the age of 18 are sent.
Uruguay further stated:
80. The Code on Children and Adolescents brings the relevant provisions into line with existing international instruments.
81. This Code applies to all persons under the age of 18, as expressed in article 1. A child (niño) is understood to mean a person up to the age of 13 and the term adolescent (adolescente) applies to persons over the age of 13 and under the age of 18, of either sex.
85. With regard to the specific theme of this Protocol [2000 Optional Protocol on the Involvement of Children in Armed Conflict], article 13 [of the Code] establishes that: “Children and adolescents may not take part in hostilities in armed conflicts or receive preparation for such purpose”.
Uruguay also stated:
8. Following a careful analysis of existing texts, no specific definition was found of “direct part in hostilities”, as understood according to the international law of armed conflict and international humanitarian law.
9. The expression may be interpreted, however, as occurring in the form of taking part in hostilities in wartime or in a state of war, which is defined in article 63 of the  Military Criminal Code as a period or situation characterized by conflict, even at times when hostilities are suspended by a truce or an armistice, whether war has been declared or not, in the course of international or internal conflicts.