Just when the "responsibility to protect" doctrine seemed to have become irretrievably tainted at the United Nations, the Security Council at last lived up to its duty to prevent mass atrocities. For the second time in three weeks, the council accomplished the politically impossible, first referring Libya to the International Criminal Court, then, yesterday, authorizing military force to protect civilians from Muammar al-Qaddafi's wrath.

What accounts for this remarkable turn of events? In part, it was the perfect villain: Qaddafi's over-the-top threats to "show no mercy" to the people of Benghazi, along with his regional meddling and megalomaniac ideas, left him few friends or defenders.

The Arab League also played an essential role by easing its usual opposition to Security Council action against its members. The league had watched silently as Sudan's Omar al-Bashir committed crimes against humanity in Darfur -- or, less recently, as Iraq's Saddam Hussein massacred Shia and Kurds, and Syria's Hafez al-Asad destroyed the town of Hama. But the league apparently sensed the winds of change wafting through the Middle East and North Africa, and felt compelled to respond. The Egyptian presidential aspirations of the leagues' secretary-general, Amr Moussa, certainly helped as well.

And of course there were the people taking to the streets throughout the region, risking their freedom and lives for the ideals of democracy and human rights that autocratic leaders had denied them for so long. Those ideals were precisely the ones practiced at home by India, Brazil, and South Africa -- emerging powers all currently on the Security Council that either supported or tacitly acquiesced in the council's action. The power of these ideas prevailed over the anti-imperialism that, anachronistically but persistently, has played a major role in these governments' foreign policies. Even Russia and China did not want to be left behind.

The challenge now is not only to translate this remarkable Security Council consensus into effective protection for Libyans. It is to extend the human rights principles embraced for Libya to other people in need. The atrocities unfolding in the Ivory Coast demand just as much attention. Other people of the Middle East and North Africa are seeing their hopes for democracy quashed by authoritarian leaders. The people of Burma and Sri Lanka have endured massive war crimes with no justice. Can the Security Council respond to their plight as well? Can it begin to recognize that a leader's atrocities against his own people are a global concern, not an internal affair? No one believes these steps will be easy, but the task before us is to translate the Security Council's principled reaction to Libya into a broader doctrine of genuine protection for people facing mass atrocities.

Foreign Policy's team of international experts debate whether Washington, London, and Paris were right to step in.