Treaties carry at least two dates. The signing is the one that gets quoted; the entry into force is recorded as a formal field by the depositary, tied to a specific article.
This note sets out the question, the fixed answer, the records that were opened, and the searches that exposed the answer and forced a rewrite.
The question as published
A founding instrument agreed at a Californian conference that closed on 26 June 1945 only took effect once five named powers and a majority of the other signatories had ratified it. On what date did it enter into force?
- Answer
- 24 October 1945
- Confidence
- High — stated by the issuing organisation and by the treaty depositary
Sources opened and read
United Nations Charter
United Nations • Intergovernmental organisation • Primary
States both competing dates in one sentence, which is what makes the distinction testable rather than a trick.
Open sourceHistory of the United Nations
United Nations • Intergovernmental organisation • Primary
Supplies the ratification condition and the four-month interval, so the answer can also be derived rather than read.
Open sourceCharter of the United Nations — treaty record
United Nations Treaty Collection • Treaty register • Primary
The strongest record in the chain: a formal depositary entry rather than an explanatory web page.
Open source
Searches that were run
when was the UN Charter signed
Google • 4 September 2026 • Answer exposed: No
Returns 26 June 1945 immediately — the decoy date, not the answer.
UN Charter entry into force date
Google • 4 September 2026 • Answer exposed: Yes
Exposes 24 October 1945 directly in the top results.
conference San Francisco April June 1945 instrument ratified five powers effective date
Google • 4 September 2026 • Answer exposed: No
Mixed conference histories; the effective date appears only after opening an organisational page.
"24 October" 1945 article 110 ratification deposit
Google • 4 September 2026 • Answer exposed: Yes
Reaches the depositary record used as E03.
What the investigation showed
What made the question difficult
Two dates compete and the more famous one — 26 June 1945 — is given in the question itself as a clue, so a careless solver simply repeats it.
Which searches failed
Queries phrased around the signing returned the decoy date only. The effective date surfaces reliably only when ratification is named.
Which source proved decisive
The depositary treaty record, because it states the effective date as a formal field tied to a specific article rather than as narrative text.
How ambiguity was removed
Naming the ratification condition rules out every other 1945 milestone, including the opening of the first General Assembly in 1946.
What an AI browsing agent might get wrong
Answering 26 June 1945, or giving 10 January 1946 by confusing entry into force with the first session.
Remaining limitations
The effective date is well indexed, so a direct query still resolves it; the difficulty comes from the wording of the question rather than from search depth.
Recommended future improvements
Require the number of ratifications deposited by that date, which is only reachable from the depositary tables.
Read the full case study
The complete record — clue matrix, evidence cards, validation log and the structured JSON output — is published on the case study page.
Open International Politics Benchmark