In an age marked by terrorism, cross-border refugee crises, and environmental catastrophes, we have witnessed how the inaction of the international community leads to horrendous outcomes—in Syria, Sudan, Myanmar, and Rwanda, to name a few. The time is ripe for giving rebirth to the doctrine of humanitarian intervention, such that it may protect civilians suffering the worst calamities in the 21st Century. This Chapter proposes three paradigms to strengthen the legal rationale behind the lawful application of military force. The paradigms expand upon the “Responsibility to Protect,” which protects civilians through non-military and military means. The first paradigm examines four opportunities under U.N. Charter law, namely, the “Responsibility Not to Veto,” the Uniting for Peace Resolution, peacekeeping actions under U.N. Charter Chapter VI, and military standby forces under Article 43 of the U.N. Charter. The second paradigm proposes a pragmatic application of the right of self-defense in the context of 21st Century realities. The third paradigm introduces the “exhaustion principle” in order to address situations where U.N. Charter procedures are exhausted and the humanitarian crisis remains dire. Each of these paradigms depends on the circumstances of human peril in order to address the all-important question, “If not now, when?”