In Berlin in the summer of 2008, United Nation’s Secretary-General Ban Ki-moon delivered one of the defining speeches of his term. He spoke of his “deep and enduring” personal commitment to the “Responsibility to Protect”—or RtoP for short. He clarified that the principle rested on three pillars of responsibility, that it was a friend not an enemy of sovereignty, and that his strategy for implementation would be narrow but deep.

In his speech, Ban defined a challenging new principle with clarity, assuaged concerns raised by many member states, and set out a bold agenda for action on the prevention of atrocity crimes and protection of vulnerable populations. The following year, the UN General Assembly adopted a resolution confirming its intention to consider implementation of RtoP. Every year since, the Assembly has received and debated a report on that subject by the secretary-general. In the three years prior to 2008, the UN Security Council had referenced RtoP only three times, in the three years after 2008 it referenced the principle nine times; today, that figure stands at ninety-one. It took the Human Rights Council until March 2008 to mention RtoP at all. Since Ban’s speech, it has passed fifty-one resolutions referencing RtoP.

Standing in the wings was the architect of the secretary-general’s campaign, Edward Luck, renowned for his astute political judgment, brilliant scholarship, and unfailing generosity of spirit. His untimely passing at the age of 72 is a source of great sorrow for his friends, colleagues, and family. Part of his enduring legacy is a UN and global community of scholars, activists, and practitioners more committed and better prepared to protect vulnerable populations from serious harm.

Throughout his life, Ed had an eye for what was important, not what was popular. He developed an early expertise on Soviet politics and foreign policy and with it a keen sense of the pluralism of international political life that served him well at the United Nations. RtoP was not the only program for human protection he helped establish at the UN. Ed worked on veto restraint a decade before it was popular and helped establish a global agenda for the protection of children in armed conflict.

His work to strengthen the UN spanned decades. Ed led the drafting of Security Council reform proposals in 1997, which included a plan to expand the Council’s membership and discourage the use of the veto. Subsequently, he continued to serve the UN as a senior consultant working on issues such as counterterrorism, the protection of children in armed conflict, and institutional reform. Ed drafted the initial reports of the UN Secretary-General’s Special Representative for Children and Armed Conflict in 1997 and 1998, setting out a bold new agenda of work on the protection of children. He helped draft Kofi Annan’s 1997 reform package, leading work on the sections on peace and security and on the structure of the secretary-general’s Office, and helped draft the UN secretary-general’s first counterterrorism strategy.

It was in his role as the secretary-general’s first Special Adviser on the Responsibility to Protect that he helped shape the principle into one that could command international respect and, more importantly, direct its practice, work that he did while serving concurrently as Senior Vice President of the International Peace Institute from 2007–2011. His work with the UN continued long after stepping down as Special Adviser, however, and in 2017–2018 he led evaluations of the work of the Special Representatives of the Secretary-General on Children and Armed Conflict and on Sexual Violence in Conflict, and on Violence Against Children.

Ed was also a gifted teacher and prodigious writer, having written and edited six books. His 2006 book on the Security Council remains among the most insightful single-authored book yet on the institution. His final book, fittingly, reflected on the responsibility to protect principle he helped develop. In both, he brought the sort of wisdom and insight to our understanding of the UN and multilateralism that comes only from deep reflection and experience, insights that will go on educating and inspiring as new students read his work.

Thoughtful, modest, and self-effacing, there was always more going on beneath the surface than was apparent above it. For example, from 2003, Ed organized and ran a workshop to help incoming and current members of the Security Council become effective members. In his years as the secretary-general’s Special Adviser on RtoP, he actively sought out the principle’s loudest critics, intent on understanding their objections, winning their confidence, and broadening and deepening consensus. Why did he, for example, use the acronym “RtoP” and not the more popular R2P? Simple: in Spanish “R2P” translates as the meaningless phrase “R-dos-P.” If the principle had any hope of surviving in the global institution it would need a shorthand the UN’s translators could make sense of.

Over long hours of careful dialogue and deliberation, for which he wasn’t compensated, Ed developed a keen understanding of why governments might be resistant to RtoP and a strategy for moving from promise to practice with the backing of the largest number of governments possible. Ed always had a sharp reading of political reality and cool sense of pragmatism, but he also had a fierce determination to leave the world in a better state than he found it. He understood that few things were more important or more difficult to achieve than turning the tide of human suffering caused by war and atrocities. He continued to work tirelessly to promote, advance, and innovate on the responsibility to protect, and with his wife  Dana developed a new concept of the individual responsibility to protect.

Ed’s brilliant intellect and immense contribution to the UN are well known, but there was also his kindness, warmth, generosity, and care. In the hundreds of messages of sympathy and condolence posted online, the same words appear again and again: “he was always so kind” wrote one civil society activist, “a kind, generous colleague” wrote a UN official, “such a kind colleague who was always willing to share knowledge and listen to junior colleagues” wrote another former UN official, a “lovely and supportive colleague. And such a brilliant mind,” one of his colleagues at Columbia University wrote, “a wonderful professor, brilliant colleague and kind mentor” wrote one of his former students. Kindness. Generosity. Warmth. These were Ed’s calling cards.

It is these qualities that he embodied in his actions, and how he channeled them into developing UN policy that helped protect the vulnerable, that will be remembered for years to come. Ed had a simple benchmark for assessing the relative merits of UN secretaries-general: did they leave the office of secretary-general stronger than they found it? There is no surprise that one he rated most highly in that respect was a secretary-general many others forget, Javier Perez de Cuellar. As he saw it, de Cuellar had navigated the organization through the choppiest of geopolitical waters and left it stronger as a result. Ed was like that. He left us all stronger than he found us. He will be sorely missed.