Human Rights Watch has an excellent Q&A on the demands of international law as they apply to the Israel/Lebanon conflict. HRW is one of the few organizations commenting on this issue which I hold in high esteem, and I think their analysis here is informative and indispensable for evaluating both Israel and Hezbollah as they prosecute this conflict.
The heads-up is from Taylor Owen, who asks if the international law, as written, is too biased in favor of institutional and state actors and makes it unreasonably difficult to fight an asymmetric war. My answer is that it may be, but unless one can come up with an alternative framework that adequately protects civilians and non-combatants from both a) being deliberately targeted and b) being used as human shields, that might be a harm I have to bite. International law properly focuses itself on the twin concerns of allowing states to defend themselves against aggression or threat, and protecting the human rights of affected parties during the course of battle. I won't say that it does a perfect job, but I do think it is solid enough to demand adherence to until we can find a better one, or unless one can give compelling evidence about why a particular exemption is justified.