MELBOURNE ― The world has watched in horror as Libya’s Colonel Muammar el-Gadhafi uses his military to attack protesters opposed to his rule, killing hundreds or possibly thousands of unarmed civilians. Many of his own men have refused to fire on their own people, instead defecting to the rebels or flying their planes to nearby Malta, so Gadhafi has called in mercenaries from neighboring countries who are more willing to obey his orders.

World leaders were quick to condemn Gadhafi’s actions. On Feb. 26, the U.N. Security Council voted unanimously to impose an arms embargo on Libya, urge member nations to freeze assets owned by Gadhafi and his family, and refer the regime’s violence to the International Criminal Court for possible prosecution of those responsible.

This is the first time that the Security Council has unanimously referred a situation involving human rights violations to the International Criminal Court, and it is remarkable that countries that are not members of the court ― including the United States, Russia, and China ― nevertheless supported the referral. The resolution can thus be seen as another incremental step towards the establishment of a global system of justice able to punish those who commit gross violations of human rights, regardless of their political or legal status in their own country.

Yet, in another way, the Security Council resolution was a disappointment. The situation in Libya became a test of how seriously the international community takes the idea of a responsibility to protect people from their rulers. The idea is an old one, but its modern form is rooted in the tragic failure to intervene in the Rwandan genocide in 1994. A subsequent U.N. inquiry concluded that as few as 2,500 properly trained military personnel could have prevented the massacre of 800,000 Tutsis.

Former U.S. President Bill Clinton has said that the mistake he most regrets making during his presidency was his failure to push for intervention in Rwanda. Kofi Annan, who was then U.N. under-secretary-general for peacekeeping operations, described the situation at the U.N. at the time as a “terrible and humiliating” paralysis.

When Annan became secretary-general, he urged the development of principles that would indicate when it is justifiable for the international community to intervene to prevent gross violations of human rights. In response, Canada’s government established an International Commission on Intervention and State Sovereignty, which recommended that military intervention could be justified, as an extraordinary measure, where large-scale loss of life is occurring or imminent, owing to deliberate state action or the state’s refusal or failure to act. These principles were endorsed by the U.N. General Assembly at its special World Summit in 2005 and discussed again in 2009, with an overwhelming majority of states supporting them.

The principle fits the situation in Libya today. Yet the Security Council resolution contains no mention of the possibility of military intervention ― not even the imposition of a no-fly zone over Libya to prevent Gadhafi from using planes to attack protesters.

One body with a special concern to transform the idea of the responsibility to protect into a cause for action is the Global Center for the Responsibility to Protect, at the City University of New York. It has called on U.N. members to uphold their 2005 commitments and put the responsibility to protect into action in Libya. It urges consideration of a range of measures, several of which were covered by the Security Council resolution, but also including a no-fly zone.

In addition to arguing that the responsibility to protect can justify military intervention, the International Commission on Intervention and State Sovereignty recommended a set of precautionary principles. For example, military intervention should be a last resort, and the consequences of action should not be likely to be worse than the consequences of inaction.

Whether these precautionary principles are satisfied in Libya requires expert judgment of the specifics of the situation. No one wants another drawn-out war like those in Iraq and Afghanistan. But Libya is not Iraq or Afghanistan ― its population is only about one-fifth of either country’s, and there is a strong popular movement for a democratic form of government. Assuming that foreign military forces rapidly overwhelmed Gadhafi’s troops, they would soon be able to withdraw and leave the Libyan people to decide their own future.

At the time of writing, it is arguable that other sanctions or threats, short of military intervention, would be sufficient to deter more widespread bloodshed. Perhaps the rebels and the sanctions can overthrow Gadhafi unaided, without great loss of life. It is also unclear whether military intervention would cause more deaths than it prevented.

But these are questions that the international community needs to ask, and that the Security Council should have been discussing, so that the principle of the responsibility to protect ― and its possible implications for military action ― become part of our understanding of the requirements of international law and global ethics.

By Peter Singer 

Peter Singer is a professor of bioethics at Princeton University and laureate professor at the University of Melbourne. His most recent book is “The Life You Can Save.” ― Ed.

(Project Syndicate)