The United States’ April 6, 2017 missile strikes against Syria raise three fundamental questions about how we should assess military interventions taken for humanitarian ends but without Security Council authorization: First, is unilateral humanitarian intervention per se illegal under international and domestic law—what I call the “never/never rule”? Second, were the Trump Administration's April 6, 2017 strikes per se illegal under international and domestic law? And third, going forward, can we live with the status quo, where in state practice, unilateral humanitarian intervention seems to occur regularly, without being formally justified in law?

In his contribution to this Symposium, Harold Koh exhorts international lawyers to “seriously engage the debate” regarding the lawfulness (or at least the legal defensibility) of humanitarian intervention (“HI”). The aim of this essay is to take him up on that plea and sketch an alternative approach to the one that he advances. In so doing, I will focus on international law rather than U.S. domestic law.

On March 19, 2011, the United States, its European allies, and its Arab partners launched an eight-month intervention in Libya. This was said to be necessary because Mu'amar Gaddafi, Libya's longtime ruler, was responding to mass protests against his over forty-year dictatorial reign by waging war on his own people. As President Barack Obama explained, without international intervention “the calls of the Libyan people for help would go unanswered. The democratic values that we stand for would be overrun. Moreover, the words of the international community would be rendered hollow.”

Article 2(4) of the UN Charter contains a general prohibition of the use of force. Articles 42 and 51 authorize departures from this prohibition in two circumstances: Security Council authorization and self-defense. These two circumstances are conceptualized as justifications. They provide for legally-warranted departures from the general rule. As a result, a justified use of force is not wrongful. Justifications are different from excuses where the action remains wrongful, but the wrongdoer may be released from responsibility for the wrongdoing.

This essay describes tensions that arise between two types of public goods enshrined in the United Nations Charter—the right to self-determination of people(s) within a territorial state and peace and security—in situations in which recognized governments in conflict-torn countries request military assistance from third states against opposition groups. It illuminates legal challenges in reconciling these public goods in practice, at a time when collective peacekeeping mechanisms appear unable to prevent or terminate civil conflicts and their destabilizing regional impact.