Related Rule
Australia
Practice Relating to Rule 7. The Principle of Distinction between Civilian Objects and Military Objectives
Australia’s Defence Force Manual (1994) provides:
210. Although not a basic principle, distinction is said to be a related principle and seeks to ensure that only legitimate military objects are attacked. Distinction has two components. The first, relating to personnel, seeks to maintain the distinction between combatants and non-combatants or civilian and military personnel. The second component distinguishes between legitimate military targets and civilian objects.
504. The law of armed conflict establishes a requirement to distinguish between combatants and civilians, and between military objectives and civilian objects. This requirement imposes obligations on all parties to a conflict to establish and maintain the distinction. …
913. The basic rule in respect of civilians which flows from this is that a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 210, 504 and 913.
Australia’s LOAC Manual (2006) states:
2.11 Although not a basic principle, distinction is said to be a related principle and seeks to ensure that only legitimate military objects are attacked. Distinction has two components. The first, relating to personnel, seeks to maintain the distinction between combatants and non-combatants or civilian and military personnel. The second component distinguishes between legitimate military targets and civilian objects. Military operations must only be conducted against military objectives, including combatants. Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack. LOAC therefore requires that belligerents maintain the clear distinction between armed forces and civilians taking no direct part in hostilities; that is, between combatants and non-combatants, and between objects that might legitimately be attacked and those protected from attack.
5.4. The LOAC establishes a requirement to distinguish between combatants and civilians, and between military objectives and civilian objects. This requirement imposes obligations on all parties to a conflict to establish and maintain the distinction …
9.13. … a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 2.11, 5.4 and 9.13.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Australia’s Defence Force Manual (1994) provides:
210. … Military operations must only be conducted against enemy armed forces and military objects. Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack. The law of armed conflict therefore requires that belligerents maintain the clear distinction between armed forces and civilians taking no direct part in hostilities; that is, between combatants and non-combatants, and between objects that might legitimately be attacked and those protected from attack.
524. Only military objectives are legitimate objects of attack. During an armed conflict, and subject to the overriding considerations of proportionality and unnecessary suffering, the ADF [Australian Defence Force] may target any military objective.
531. There is a fundamental rule that parties to a conflict must direct their operations only against military objectives. …
913. The basic rule in respect of civilians which flows from this is that a distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be carried out against military objectives. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 210, 524, 531 and 913.
Australia’s LOAC Manual (2006) states:
2.11 … Military operations must only be conducted against military objectives, including combatants.
5.26 Only military objectives are legitimate objects of attack. During an armed conflict, and subject to the overriding considerations of proportionality and unnecessary suffering, the ADF [Australian Defence Force] may target any military objective.
5.35 There is a fundamental rule that parties to a conflict must direct their operations only against military objectives.
9.13 … [A] distinction must be made between the civilian population and combatants, and between civilian objects and military objectives, in order that military operations will only be directed against military objectives. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 2.11, 5.26, 5.35 and 9.13; see also §§ 6.37 and 9.17.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Upon ratification of the 1977 Additional Protocol I, Australia declared:
It is the understanding of Australia that the first sentence of paragraph 2 of Article 52 is not intended to, nor does it, deal with the question of incidental or collateral damage resulting from an attack directed against a military objective. 
Australia, Declarations made upon ratification of the 1977 Additional Protocol I, 21 June 1991, § 5.
Australia’s Defence Force Manual (1994) provides:
Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack. The law of armed conflict therefore requires that belligerents maintain the clear distinction between armed forces and civilians taking no direct part in hostilities; that is, between combatants and non-combatants, and between objects that might legitimately be attacked and those protected from attack. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 210; see also § 503(b) and 531.
Australia’s LOAC Manual (2006) states:
2.11 … Non-combatants and civilian objects are protected from attack, that is, they are not legitimate objects of attack …
9.17 Military operations may only be directed against military objectives and not against the civilian population and civilian objects. …
9.18 It follows from the general rule that it is forbidden to attack the civilian population, individual civilians and civilian objects as a deliberate method of warfare. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 2.11 and 9.17–9.18; see also §§ 5.3 and 5.35.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
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:
268.36 War crime – attacking civilian objects
A person (the perpetrator) commits an offence if:
(a) the perpetrator directs an attack; and
(b) the object of the attack is not a military objective; and
(c) the perpetrator’s conduct takes place in the context of, and is associated with, an international armed conflict.
Penalty: Imprisonment for 15 years. 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.36, p. 326.
Australia’s ICC (Consequential Amendments) Act (2002) incorporates in the Criminal Code the war crimes defined in the 1998 ICC Statute, including “attacking civilian objects” in international armed conflicts. 
Australia, ICC (Consequential Amendments) Act, 2002, Schedule 1, § 268.36.
Australia’s Commanders’ Guide (1994) states:
Civilian vessels, aircraft, vehicles and buildings may be lawfully attacked if they contain combatant personnel, military equipment, supplies or are otherwise associated with combat activity inconsistent with their civilian status. 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 951.
Australia’s Defence Force Manual (1994) states:
Civil aircraft in flight (including state aircraft which are not military aircraft) should not be attacked. They are presumed to be carrying civilians who may not be made the object of direct attack. If there is doubt as to the status of a civil aircraft, it should be called upon to clarify that status. If it fails to do so, or is engaged in non civil activities, such as ferrying troops, it may be attacked. Civil aircraft should avoid entering areas which have been declared combat zones by the belligerents.
Civil aircraft which have been absorbed into a belligerent’s air force and are being ferried from the manufacturer to a belligerent for this purpose, may be attacked. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, §§ 852 and 853.
Australia’s LOAC Manual (2006) states in its chapter on “Maritime Operations”:
6.39 Enemy merchant vessels. Enemy merchant vessels may only be attacked if they meet the definition of military objective.
6.40 Enemy civil aircraft. Enemy civil aircraft may likewise only be attacked if they meet the definition of a military objective.
6.44 Classes of vessels exempt from attack. The following classes of enemy vessels are exempt from attack:
• passenger vessels when engaged only in carrying civilian passengers;
6.56 The destruction of enemy passenger vessels carrying only civilian passengers is prohibited at sea. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 6.39, 6.40, 6.44 and 6.56.
In its chapter on “Air Operations”, the manual states:
8.56 Civil aircraft in flight (including state aircraft, which are not military aircraft) should not be attacked. They are presumed to be carrying civilians who may not be made the object of direct attack. If there is doubt as to the status of a civil aircraft, it should be called upon to clarify that status. If it fails to do so, or is engaged in non-civil activities, such as ferrying troops, it may be attacked. Civil aircraft should avoid entering areas that have been declared conflict zones by the belligerents.
8.57 Civil aircraft, which have been absorbed into a belligerent’s air force and are being ferried from the manufacturer to a belligerent for this purpose, may be attacked.
8.59 Civil aircraft on the ground may only be attacked in accordance with the normal rules relating to military objectives. However, since they may be used for transporting troops or supplies, their status will frequently depend upon the prevailing military situation. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 8.56–8.57 and 8.59.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).