This chapter aims at assessing whether HRC fact-finding missions are legally able to assess the violation of certain rules pertaining to the principle of precaution in attack in the absence of cooperation of the concerned attackers. In particular, the question is whether HRC fact-find missions can reach any conclusion through inference in relation to alleged violations of Article 57(2)(a)(i) and (ii) of the 1977 First Additional Protocol (API), which embody the duty to verify in advance the objective and expected consequences of an attack, and to choose means and methods of warfare that avoid or minimise incidental civilian casualties or damages. Since these duties bind ‘those who plan or decide upon an attack’ and compliance is dependent on the information available to them before the attack, it may be argued that the lack of cooperation of the attackers may impair the ability of fact-finding missions to assess respect for these rules. Nonetheless, some HRC fact-find missions have offered conclusions on the violations of these duties based on inference. Since these conclusions have raised some criticism, it is necessary to explore in more details whether international law permits HRC fact-find missions to ascertain through inference that the rules under Article 57(2)(a)(i) and (ii) of the API have been violated.