Related Rule
Australia
Practice Relating to Rule 137. Participation of Child Soldiers in Hostilities
Australia’s Defence Force Manual (1994) provides: “Children are granted special protection under LOAC. Important rules are shown below: … children under 15 years of age should not take a direct part in hostilities.” 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 947.
Australia’s Defence Instructions (General) (2005) states:
11. … [A]ll feasible measures are to be taken to ensure that minors are not deployed to an area of hostilities. That is, to the maximum extent possible, and where it will not adversely impact on the conduct of operations, minors should not be deployed into areas of operations where there is a likelihood of hostile action.
12. Where a minor is on the strength of a unit that is required to deploy to an area of hostility, that minor is not to deploy with the unit. In the case of a unit that is in transit or on exercise, and is required to deploy at short notice, minors in that unit must be returned to a safe area without undue delay.
13. A commander is not obliged to remove a minor from direct participation in hostilities where:
a. circumstances beyond the control of the commander do not permit removal,
b. where it would be more dangerous to the minor to attempt to do so, or
c. where it would prejudice the effectiveness of the mission.
However, nothing in this paragraph relieves a commander of the obligation to do everything possible within their power to prevent minors from participating directly in hostilities.
14. There should be very few circumstances in which the above requirement could not be met. The most obvious exception relates to Navy. Where a minor is serving in a ship that is diverted at short notice to an area of hostility, and it is not possible for that minor to be landed at the nearest safe port prior to the vessel continuing to the area of operations, that minor is to remain with their ship. 
Australia, Defence Instructions (General) PERS 33-4, Recruitment and employment of members under 18 years in the Australian Defence Force, Department of Defence, Canberra, 4 July 2005, §§ 11–14.
Australia’s LOAC Manual (2006) states that “children under 18 years of age should not take a direct part in hostilities”. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 9.50.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Australia’s Defence Instructions (General) (2008) states:
Deployment into hostilities
47. In accordance with Defence’s obligations under the Protocol [2000] Optional Protocol on the Involvement of Children in Armed Conflict], Services must take all feasible measures to ensure that minors do not participate in hostilities. That is, to the maximum extent possible, and where it will not adversely impact on the conduct of operations, minors should not be deployed into areas of operations where there is a likelihood of hostile action.
48. Where a minor is part of a unit that is required to deploy to an area of hostility, that minor is not to deploy with the unit. In the case of a unit that is in transit or on exercise, and is required to deploy at short notice, minors in that unit must be returned to a safe area without undue delay.
49. A CO [commanding officer] is not obliged to remove a minor from direct participation in hostilities where:
a. circumstances beyond the control of the CO do not permit removal,
b. it would be more dangerous to the minor to attempt to do so, or
c. it would prejudice the effectiveness of the mission.
50. However, nothing in paragraph 49. relieves a CO of the obligation to do everything possible within their power to prevent minors from participating directly in hostilities. 
Australia, Defence Instructions (General) PERS 33-4, Management and administration of Australian Defence Force members under 18 years of age, Department of Defence, Canberra, 22 April 2008, §§ 47–50.
In the list of definitions provided with the Defence Instructions (General), a “minor” is defined as “a person under the age of 18 years”. 
Australia, Defence Instructions (General) PERS 33-4, Management and administration of Australian Defence Force members under 18 years of age, Department of Defence, Canberra, 22 April 2008, Annex A.
This edition of the Defence Instructions (General) replaces the Defence Instructions (General) (2005).
Australia’s Criminal Code Act (1995), as amended to 2007, states with respect to serious war crimes that are committed in the course of an international armed conflict:
268.68 War crime – using, conscripting or enlisting children
National armed forces
(1) A person (the perpetrator) commits an offence if:
(a) the perpetrator uses one or more persons to participate actively in hostilities as members of the national armed forces; and
(b) the person or persons are under the age of 15 years; and
(c) the perpetrator’s conduct takes place in the context of, and is associated with, an international armed conflict.
Penalty: Imprisonment for 17 years.
Other armed forces and groups
(4) A person (the perpetrator) commits an offence if:
(a) the perpetrator uses one or more persons to participate actively in hostilities other than as members of the national armed forces; and
(b) the person or persons are under the age of 18 years; and
(c) the perpetrator’s conduct takes place in the context of, and is associated with, an international armed conflict.
Penalty: Imprisonment for 17 years. 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.68, pp. 345–347.
The Criminal Code Act also states with respect to war crimes that are other serious violations of the laws and customs applicable in a non-international armed conflict:
268.88 War crime – using, conscripting or enlisting children
National armed forces
(1) A person (the perpetrator) commits an offence if:
(a) the perpetrator uses one or more persons to participate actively in hostilities as members of the national armed forces; and
(b) the person or persons are under the age of 15 years; and
(d) the perpetrator’s conduct takes place in the context of, and is associated with, an armed conflict that is not an international armed conflict.
Penalty: Imprisonment for 17 years.
Other armed forces and groups
(4) A person (the perpetrator) commits an offence if:
(a) the perpetrator uses one or more persons to participate actively in hostilities other than as members of the national armed forces; and
(b) the person or persons are under the age of 18 years; and
(c) the perpetrator’s conduct takes place in the context of, and is associated with, an armed conflict that is not an international armed conflict.
Penalty: Imprisonment for 17 years. 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.88, pp. 363–365.
Australia’s ICC (Consequential Amendments) Act (2002) incorporates in the Criminal Code the war crimes defined in the 1998 ICC Statute, including the use of one or more persons under the age of 15 years “to participate actively in hostilities” in both international and non-international armed conflicts. 
Australia, ICC (Consequential Amendments) Act, 2002, Schedule 1, §§ 268.68 and 268.88.
In 2008, 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, Australia stated:
6. Australia signed the Optional Protocol on 21 October 2002, and ratified it in September 2006. It entered into force for Australia on 26 October 2006, pursuant to article 10(2) of the Optional Protocol.
15. … Australia considers that the … use of persons under 18 as soldiers remains a serious problem for the international community. …
24. The Australian Government interprets this article to mean that persons under 18 years of age should not be deployed to areas where there is a likelihood of hostilities. …
46. … [T]he Commonwealth Criminal Code, sections 268.68 and 268.88 make the war crime of using … children in an armed conflict an offence under Australian law. Section 268.68 refers to international armed conflict and section 268.88 refers to non-international armed conflict and both provisions have extraterritorial effect. The various offences under these sections carry maximum penalties of 17 years, 15 years and 10 years imprisonment. 
Australia, Initial report to the Committee on the Rights of the Child under the Optional Protocol on the Involvement of Children in Armed Conflict, 15 September 2010, UN Doc. CRC/C/OPAC/AUS/1, submitted October 2008. §§ 6, 15, 24 and 46.
In 2009, in response to a question on notice before the Senate concerning whether members of Australia’s armed forces under the age of 18 years have taken part in military operations, Australia’s Minister for Defence stated:
Since 21 October 2002, no member of the ADF [Australian Defence Force] under the age of 18 has taken part in warlike military operations. Defence policy restricts the employment of personnel under 18 years of age on operations where hostile action is likely. When available, ADF members under 18 years of age routinely participate in operations that do not involve armed hostilities, such as providing aid to the civil community. 
Australia, Senate, Minister for Defence, Question on notice: Australian Defence Force, Hansard, 17 August 2009, p. 5111.
In 2010, in a statement before the UN Human Rights Council on the Democratic Republic of the Congo (DRC), the representative of Australia stated: “[Australia is] concerned that certain elements within the DRC’s armed forces continue to use … children. We support the Experts’ recommendation that the Government should prepare and implement an action plan for the prevention of … [the] use of child soldiers.” 
Australia, Statement by its representative before the UN Human Rights Council, 13th Regular Session, Interactive Dialogue with Experts on the Situation in the Democratic Republic of the Congo, 24 March 2010.
In 2010, in a statement before the UN Human Rights Council on Somalia, the representative of Australia stated:
Australia … [is] deeply concerned by his [the Independent Expert’s] observation that the situation for … children in Somalia has become more precarious. In particular, we note the Independent Expert’s report of … the continued … use of child soldiers. We support the Independent Expert’s call for all parties in the conflict – government and opposition groups – to respect basic principles of human rights and humanitarian law. 
Australia, Statement by its representative before the UN Human Rights Council, 13th Regular Session, Interactive Dialogue on the Situation of Human Rights in Somalia, 24 March 2010.