The UN Security Council and its veto, explained

The United Nations Security Council is the only body in international law that can authorise military force, impose binding sanctions, or refer situations to international courts on behalf of the international community. It has fifteen members, but five of them hold a power the other ten do not: the right of veto. A single veto from any of the five permanent members kills a resolution, regardless of how the other fourteen vote. That asymmetry shapes almost every major international crisis.

How the Security Council is structured

The five permanent members, known as the P5, are the United States, the United Kingdom, France, Russia, and China. Their permanent seats reflect the post-World War Two settlement; they were the principal victorious powers and the first to possess nuclear weapons. The remaining ten seats rotate among other UN member states, with elections held in the General Assembly, typically for two-year terms. Resolutions require nine affirmative votes plus no veto from any P5 member to pass.

How the veto works in practice

The veto does not need to be used for it to shape outcomes. The credible threat of a veto is often enough to prevent a resolution from even being tabled, or to water down its language until it is acceptable. This is called the shadow of the veto. When the Security Council does reach agreement, it can authorise peacekeeping missions, arms embargoes, travel bans, asset freezes, and other binding measures. When it cannot, as happens frequently on matters involving great-power interests, the Council is effectively paralysed.

The veto has been used hundreds of times since 1945. In many periods, Russia and the United States each used it most frequently, typically to protect allied governments or their own interests from Council action.

Why reform is so difficult

Many countries argue the Council is unrepresentative. Africa, Latin America, and South Asia between them contain the majority of the world's population but have no permanent seats. Nations including Germany, Japan, India, and Brazil have long sought permanent membership. Any reform requires an amendment to the UN Charter, which itself must be ratified by all five current permanent members. Each P5 country has an interest in preserving the existing arrangement, which gives it a unique veto over its own removal. This is why structural reform has made very little progress in eighty years.

What it means for Australia

Australia participates in the UN system as a committed multilateralist and has held non-permanent Security Council seats in the past. When the Council is deadlocked, the options available to coalitions of countries to respond to crises become limited and legally murkier. Australia has been involved in military operations authorised by the Council as well as coalitions acting outside it. Understanding the veto helps Australians understand why some international crises produce coordinated responses and others produce years of inaction.

The bottom line

The veto was designed to keep the great powers inside the UN system rather than outside it, but it also guarantees that the Council cannot act against the fundamental interests of any P5 member. That trade-off is not a bug; it was the founding compromise.

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