On June 26, 1945, in San Francisco, 50 states signed the Charter of the United Nations — the UN’s founding treaty and a post‑World War II attempt to prevent another breakdown of international order.
What happened
- The San Francisco Conference (April–June 1945) negotiated the final text.
- The Charter set out the UN’s purposes and principles and created core institutions: the General Assembly, Security Council, International Court of Justice, and others.
- It entered into force on October 24, 1945, after the required ratifications.
Why it matters
- It is the baseline legal architecture of the post‑1945 system: sovereign equality, limits on the use of force (with narrowly defined exceptions), and collective security.
- For decades, it shaped what states could plausibly claim as “lawful” action — and what the rest of the world could treat as illegitimate.
Key takeaway
The Charter is not just a set of prohibitions: it is a political‑legal compromise designed to make state behavior more predictable through shared rules, while acknowledging power realities (notably the Security Council’s role).