It is widely accepted that a state cannot treat a struggle with an organized non‐state actor as an armed conflict until the violence crosses a minimum threshold of intensity. For instance, during the recent standoff at the Oregon wildlife refuge, the U.S. government could have lawfully used force pursuant to its domestic law enforcement and human rights obligations, but President Obama could not have ordered a drone strike on the protesters. The reason for this uncontroversial rule is simple—not every riot or civil disturbance should be treated like a war.
But what if President Obama had invited Canada to bomb the protestors—once the United States consented, would all bets be off? Can an intervening state use force that would be illegal for the host state to use itself? The silence on this issue is dangerous, in no small part because these once‐rare conflicts are now commonplace. States are increasingly using force against organized non‐state actors outside of the states’ own territories—usually, though not always, with the consent of the host state. What constrains the scope of the host state’s consent? And can the intervening state always presume that consent is valid?
This Article argues that a host state’s authority to consent is limited and that intervening states cannot treat consent as a blank check. Accordingly, even in consent‐based interventions, the logic and foundational norms of the international legal order require both consent‐giving and consent‐receiving states to independently evaluate what legal regime governs—this will often turn on whether the intensity threshold has been met. If a non‐international armed conflict exists, the actions of the intervening state are governed by international humanitarian law; if not, its actions are governed instead by its own and the host state’s human rights obligations.