Related Rule
Australia
Practice Relating to Rule 18. Assessment of the Effects of Attacks
Australia’s Defence Force Manual (1994) states that those responsible for deciding upon an attack must refrain from “launching any attack which may be expected to cause collateral injury, or collateral damage, which would be excessive in relation to the concrete and direct military advantage anticipated”. 
Australia, Manual on Law of Armed Conflict, Australian Defence Force Publication, Operations Series, ADFP 37 – Interim Edition, 1994, § 556(f); see also Law of Armed Conflict, Commanders’ Guide, Australian Defence Force Publication, Operations Series, ADFP 37 Supplement 1 – Interim Edition, 7 March 1994, § 957(c).
Australia’s LOAC Manual (2006) states that it is the duty of Australian Defence Force commanders to refrain “from launching any attack which may be expected to cause collateral injury, or collateral damage, which would be excessive in relation to the concrete and direct military advantage anticipated”. 
Australia, The Manual of the Law of Armed Conflict, Australian Defence Doctrine Publication 06.4, Australian Defence Headquarters, 11 May 2006, § 5.61.
The LOAC Manual (2006) replaces both the Defence Force Manual (1994) and the Commanders’ Guide (1994).