The claims in three cases against the UK's Ministry of Defence (MoD) arose from military operations in Iraq, in which soldiers were either killed or seriously injured: Smith v Ministry of Defence, Ellis v Ministry of Defence, Allbutt v Ministry of Defence,  UKSC 41. One issue was the application of the European Convention on Human Rights, which is not of particular relevance to us in Canada; the claims framed in negligence are, however, of considerable interest.
The Crown and its agents enjoy what has been called 'combat immunity', which is a shield from liability for negligence in the heat of battle that is predicated on the assumption that it would be unfair, unjust and unreasonable to impose liability for decisions taken or omissions made in the context of active combat. But the claims in these appeals were different: it was alleged that the MoD had been negligent in failing to provide equipment that would have prevented the injuries and deaths in question, some of which resulted from so-called 'friendly fire' ('mistakenly hostile fire' would be a more accurate description); the argument was that combat immunity ought not to apply to negligence in procurement and pre-battle planning. The 4-3 majority in the UK Supreme Court concluded that the negligence claims could proceed to trial. The circumstances of actual military engagement are different from the training and provision of equipment that occur in preparation for it (and perhaps from peacekeeping operations), and the policy reasons for combat immunity are absent before the fighting has actually begun.
Three law lords dissented, on the grounds that the majority (and the courts below) had underestimated 'the inevitable inter-linking' of pre-deployment issues with 'decisions taken on the ground during active service'. Policy required immunity from liability in the planning and preparation of operations, as well in their execution; otherwise, the armed forces will be subject to the spectre of litigation and hampered in their ability to make decisions. There is also discussion in the majority and dissenting reasons of immunity and liability in the context of police and emergency services.