The rapid evolution of cyber capabilities has not only enabled huge advancement in human technology but has also challenged the capacity of legal systems to govern such activities. As cyber operations become an increasing cause of diplomatic tension and a fixture of armed conflicts, setting limits on when such activities will be considered lawful is a priority for States. At a domestic level, the creation of new regimes of law may be comparatively fast-tracked by legislatures to keep up with technological change. However, this is more challenging at an international level, as customary law develops only incrementally and new treaty instruments remain rare. One way that international law can adapt is by the capacity for interpretation of existing treaty instruments to evolve over time. This chapter examines emerging State practice which has begun to reinterpret how longstanding international humanitarian law rules apply to cyber operations and demonstrated a growing consensus about when cyber activities may be considered to violate these key limits.