Killing Within the Rules

It is generally accepted that rules are important, even in war, and that the adherence to them is one of the ways that the West differentiates itself from the terrorists it seeks to destroy. However, what exactly are the rules and how have they changed? In the light of high profile rulings by the UK Law Lords on the applicability of human rights legislation in theatres of military operations, some are claiming that the British military is under legal siege and is increasingly unable to do its job due to new rules, interference from lawyers and the fear of looking over one's shoulder. Is this view accurate?