When U.N. Secretary General Ban Ki-moon invoked diplomatic immunity last week for peacekeepers who unwittingly caused the cholera outbreak that killed nearly 8,000 Haitians, his decision looked cold-hearted. Many in Haiti and in the humanitarian community are indignant that the United Nations will face no consequences for failing to properly test soldiers from Nepal who assisted in earthquake relief efforts in 2010. The incident seems like a sign of arrogance and ineptitude on the U.N.’s part.

But sympathy for Haitians should not mask the necessity of the secretary-general’s decision. It was right as a legal matter — and as a moral one, too.

While causation is not easily proved, the evidence overwhelmingly suggests that a strain of cholera was introduced by peacekeepers from Nepal; sewage from their base contaminated the Artibonite River, causing the spread of a disease that had been absent from Haiti for a century. About one in every 16 Haitians is now infected.

The case against the United Nations was brought by the Boston-based Institute for Justice and Democracy in Haiti. The U.N. has never acknowledged its culpability in the outbreak and has been unforgivingly hostile to what amounts to near scientific certainty.

Last week, Ban called Haitian President Michel Martelly to inform him that the U.N. was invoking Article 29 of the Convention on the Privileges and Immunities of the United Nations. The case is historic: The organization rarely asserts immunity for itself but merely enforces the privileges for member nations.

The convention serves as the foundation of a formal international legal regime envisioned at the U.N.’s inception after World War II. Codified as the Vienna Convention on Diplomatic Relations in 1961, it grants diplomats and those who work in a diplomatic capacity certain immunities from harm or litigation in a host country so that, in return, the honor would be reciprocated. This is not just a modern phenomenon. Evidence of diplomatic immunity is found in historical tales from India dating back to 500 BC.

Hard cases, the expression goes, make bad law. But there are instances when they can reinforce good law. This case is about disaster management, not public health. The soldiers from Nepal were in Haiti to help stabilize a nation that was suffering.

Putting aside whether the U.N.’s attitude has been sympathetic enough; whether it should vet peacekeeping forces better before deploying them; and whether the organization has a moral obligation to give Haiti more help with its public health needs, Ban’s decision will protect all relief efforts in the future.

It is the only outcome that provides the necessary protections to those who are asked to work voluntarily in dangerous situations. Most importantly, it will maintain an incentive for nations to support U.N. efforts for assistance or peacekeeping missions that have, by any measure, done far more good than harm.

There are two sides to globalization. The bad side, as is evident in Haiti, is that once-isolated microbes can kill victims across the globe, especially in places where sanitation and clean water are lacking. The beneficial side is that when a nation needs the global community to respond after a horrible earthquake, public safety resources and medical expertise are available.

Diplomatic immunity for the U.N. soldiers was a necessity to protect international development and disaster efforts in the future. Ban’s decision protects not only the U.N. but also all those who serve internationally in capacities that might otherwise subject them to the whims of local politicians and judges. Such immunity ought not to protect all behavior. But had this case led to a trial pitting the U.N., Nepal, and Haiti against one another, the consequences for the next disaster would be devastating. It would open the door for challenges to international relief and public health efforts, either through litigation against the U.N. or, worse, against individual soldiers, emergency managers, and public health workers.

We can never know now the answer to the dilemma that the outbreak raises: How does one measure the unfolding cholera crisis against the life-saving measures during the response to the earthquake that killed, by Haiti’s count, over 300,000 of its citizens?

The U.N.’s assertion of immunity might be tragic for a nation that has had its fair share of tragedy. But it is absolutely right.

Juliette Kayyem is a columnist for the Boston Globe and lecturer in public policy at Harvard’s Kennedy School of Government.