Related Rule
Australia
Practice Relating to Rule 6. Civilians’ Loss of Protection from Attack
Section A. Direct participation in hostilities
Australia’s Defence Force Manual (1994) states: “Civilians are only protected as long as they refrain from taking a direct part in hostilities.” 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 532; see also §§ 527 and 918.
The manual further states: “Whether or not a civilian is involved in hostilities is a difficult question which must be determined by the facts of each individual case. Civilians bearing arms and taking part in military operations are clearly taking part in hostilities.” 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 532.
Australia’s LOAC Manual (2006) states: “Civilians are only protected as long as they refrain from taking 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, § 5.36; see also § 2.11.
The manual further states:
Whether or not a civilian is involved in hostilities is a difficult question, which must be determined by the facts of each individual case. Civilians bearing arms and taking part in military operations are clearly taking part in hostilities; civilians working in a store on a military air base may not necessarily be taking such a direct part. However, stores depots, supply columns and military installations are clearly military objectives which may be attacked, regardless of the presence of civilian workers. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.36.
The manual also states that “civilians who take part in the conflict become unlawful combatants and legitimate targets”. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 9.18.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).