Related Rule
Australia
Practice Relating to Rule 46. Orders or Threats That No Quarter Will Be Given
Australia’s Commanders’ Guide (1994) states: “It is expressly forbidden to announce or implement a plan under which no prisoners are taken.” 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 416.
The Guide further states:
It is prohibited to order that no prisoners will be taken, threaten an enemy that such an order will be given or conduct hostilities on the basis that no prisoners will be taken. Ambiguous orders, such as, “take that objective at any cost” should be avoided. 
Australia, Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 905.
Australia’s Defence Force Manual (1994) provides:
It is prohibited to order that no prisoners will be taken, threaten an enemy that such an order will be given or conduct hostilities on the basis that no prisoners will be taken. Ambiguous orders, such as, “take that objective at any cost” should be avoided. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 706 (land warfare); see also § 835 (air warfare).
Australia’s LOAC Manual (2006) states:
7.7 It is prohibited to order that no prisoners will be taken, threaten an enemy that such an order will be given or conduct hostilities on the basis that no prisoners will be taken. Ambiguous orders, such as, “take that objective at any cost”, should be avoided.
13.29 Provisions of the Hague Regulations 1907 are now recognised as part of customary law. Those regulations provide that the following acts are “especially forbidden”:
• to declare that no quarter will be given. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, §§ 7.7 and 13.29; see also § 8.39.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).
Australia’s War Crimes Act (1945) considers “any war crime within the meaning of the instrument of appointment of the Board of Inquiry [set up to investigate war crimes committed by enemy subjects]” as a war crime, including directions to give no quarter. 
Australia, War Crimes Act, 1945, Section 3.
Australia’s Criminal Code Act (1995), as amended to 2007, states with regard to serious war crimes that are committed in the course of an international armed conflict:
268.50 War crimedenying quarter
A person (the perpetrator) commits an offence if:
(a) the perpetrator declares or orders that there are to be no survivors; and
(b) the declaration or order is given with the intention of threatening an adversary or conducting hostilities on the basis that there are to be no survivors; and
(c) the perpetrator is in a position of effective command or control over the subordinate forces to which the declaration or order is directed; and
(d) the perpetrator’s conduct takes place in the context of, and is associated with, an international armed conflict.
Penalty: Imprisonment for life. 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.50, p. 334.
The Criminal Code Act also states with regard to war crimes that are violations of the laws and customs of war applicable in a non-international armed conflict:
268.91 War crimedenying quarter
A person (the perpetrator) commits an offence if:
(a) the perpetrator declares or orders that there are to be no survivors; and
(b) the declaration or order is given with the intention of threatening an adversary or conducting hostilities on the basis that there are to be no survivors; and
(c) the perpetrator is in a position of effective command or control over the subordinate forces to which the declaration or order is directed; 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 life. 
Australia, Criminal Code Act, 1995, as amended to 2007, Chapter 8, § 268.91, p. 366.
Australia’s ICC (Consequential Amendments) Act (2002) incorporates in the Criminal Code the war crimes defined in the 1998 ICC Statute, including declaring or ordering that there are to be no survivors with the intention of threatening an adversary or conducting hostilities on this basis, both in international and non-international armed conflicts. 
Australia, ICC (Consequential Amendments) Act, 2002, Schedule 1, §§ 268.50 and 268.91.
In its oral pleadings before the ICJ in the Nuclear Weapons case in 1995, Australia stated that the “right to self-defence is not unlimited … Self-defence is not a justification … for ordering that there shall be no enemy survivors in combat.” 
Australia, Oral pleadings before the ICJ, Nuclear Weapons case, 30 October 1995, Verbatim Record CR 95/22, p. 52.