GLOSSARY
The UN Security Council: what it is, how it works, and why a single “no” can block everything
Updated July 22, 2026
The Security Council appears often on this site as the place where an international law initiative stalls. It’s worth understanding why: its voting structure makes it possible for a single objection to block a decision supported by every other member.
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Read the explainerWhat it is
The Security Council is the UN body responsible for maintaining international peace and security, established by the UN Charter in 1945. It has 15 members: 5 permanent — the United States, Russia, China, the United Kingdom, and France — and 10 non-permanent members, elected by the General Assembly for two-year terms.
How it works
Decisions on substantive matters require at least 9 votes in favor out of 15 — but with one condition that overrides everything else: none of the five permanent members can vote against (Article 27(3) of the UN Charter). A single “no” from any one of the five blocks the resolution, no matter how many other states support it. This is the veto. It does not apply to purely procedural matters.
Why it exists
The veto is not a design flaw: it was the price agreed in 1945 to keep the five wartime victors inside the UN system, after the League of Nations had failed precisely because it lacked a similar safeguard and the great powers gradually disengaged from it. Without that guarantee, the US and the USSR would likely never have joined.
The limit, in practice
In November 2024, Russia vetoed a resolution calling for an immediate ceasefire in Sudan — the only “no” vote out of 15. The United States has vetoed at least six resolutions calling for a ceasefire in Gaza between 2023 and 2025, often with 13 or 14 states in favor out of 15. In both cases a single vote stopped an overwhelming majority — not because of a technicality, but because the system was built precisely to allow it.
Why it matters for this site
Whenever a piece here mentions a Security Council referral to the International Criminal Court, or the lack of consequences for an unenforced ruling by the International Court of Justice, the point is the same: a permanent member protecting itself or an ally can block action alone, regardless of what the other 14 think.
Sources: UN Charter · Security Council Report · UN Press · Al Jazeera