Règle correspondante
Canada
Practice Relating to Rule 15. The Principle of Precautions in Attack
Section D. Information required for deciding upon precautions in attack
Canada’s LOAC Manual (1999) states:
Decisions will be based on the “circumstances ruling at the time”. Consideration must be paid to the honest judgement of responsible commanders, based on the information reasonably available to them at the relevant time, taking fully into account the urgent and difficult circumstances under which such judgements are usually made. 
Canada, The Law of Armed Conflict at the Operational and Tactical Level, Office of the Judge Advocate General, 1999, pp. 4-3/4-4, § 26.
Canada’s LOAC Manual (2001) states in its chapter on targeting:
418. Standard of care
1. Commanders, planners and staff officers will not be held to a standard of perfection in reaching their decisions.
2. Commanders, planners and staff officers are required to take all “feasible” steps to verify that potential targets are legitimate targets. However, such decisions will be based on the “circumstances ruling at the time”. Consideration must be paid to the honest judgement of responsible commanders, based on the information reasonably available to them at the relevant time, taking fully into account the urgent and difficult circumstances under which such judgements are usually made.
3. The test for determining whether the required standard of care has been met is an objective one: Did the commander, planner or staff officer do what a reasonable person would have done in the circumstances? 
Canada, The Law of Armed Conflict at the Operational and Tactical Levels, Office of the Judge Advocate General, 13 August 2001, § 418.1–3.
Canada’s Use of Force Manual (2008), in a section entitled “Principles and rules governing the use of force that directly relates to the conduct of armed conflict”, states:
Standard of care. … Decisions concerning the use of force shall be reached on the basis of an assessment of the information reasonably available at the relevant time and that such decisions cannot be judged on the basis of information which has subsequently come to light. Reasonable, good faith efforts must be made to gather intelligence and to review the available intelligence. 
Canada, Use of Force for CF Operations, Canadian Forces Joint Publication, Chief of the Defence Staff, B-GJ-005-501/FP-001, August 2008, § 112.6.
At the CDDH, Canada stated:
Commanders and others responsible for planning, deciding upon or executing necessary attacks, have to reach decisions on the basis of their assessment of whatever information from all sources may be available to them at the relevant time. 
Canada, Statement at the CDDH, Official Records, Vol. VI, CDDH/SR.41, 26 May 1977, p. 178.
Upon ratification of the 1977 Additional Protocol I, Canada stated:
It is the understanding of the Government of Canada that, in relation to Articles 48, 51 to 60 inclusive, 62 and 67, military commanders and others responsible for planning, deciding upon or executing attacks have to reach decisions on the basis of their assessment of the information reasonably available to them at the relevant time and that such decisions cannot be judged on the basis of information which has subsequently come to light. 
Canada, Reservations and statements of understanding made upon ratification of the 1977 Additional Protocol I, 20 November 1990, § 7.