In the course of its three massive onslaughts against the besieged Gaza Strip between 2008-14, Israel has worked to reshape the customary law of proportionality in irregular combat. Article 51(5)(b) of the First Additional Protocol prohibits an attack “which may be expected to cause incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated.” Israel has attempted to re-shape the scope of proportionality in the conduct of hostilities in ways that expand the tolerable level of harm caused in at least three ways. One, it pushed back on the meaning of military advantage so that it does not strictly refer to the advantage during a single operation but instead what an attack would mean to the overall military advantage. It did so, by adopting a forward-looking military advantage. Two, it adopted a radical definition of force protection, the military value of protecting a belligerent’s armed forces. Israel claimed that its soldiers’ lives to be more valuable than those of enemy civilians, thus shifting the burden of warfare to enemy civilians and tolerating greater loss of life under a proportionality assessment. Three, it helped redefine when, and for how long, a civilian becomes a direct participant in hostilities (DPH) and thus a legitimate target. Whereas, the traditional definition made civilians a legitimate target “for such time as they take up arms,” Israel’s jurisprudence and operational practice expanded that temporal scope to legitimate killing civilians even when they were not engaged in combat and posed no risk. In doing so, Israel has legally justified launching attacks against “targets” in their homes as they slept surrounded by civilian members of their family and other civilian inhabitants of their residential buildings. To examine these shifts, I will be looking at Israel’s operational practice as documented by testimony from Israeli soldiers as well as several fact-finding missions deployed to investigate the conduct of hostilities. In addition, I will be taking a close look at Israel’s interventions in shaping opinion juris as captured by its participation in the International Committee for the Red Cross’s Interpretive Guidance on DPH, Israeli jurisprudence, as well as individual scholarly contributions that have had a tremendous impact on Israel’s military practice.