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AI Labs · Last updated 7 Jun 2026 · methodology v2.1 · Hallucination Register

Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON

RLB Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46
What the RLB Specialist Panel found

Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON

  • Question (paraphrased to protect IP): What does Section VIII.c of the 2025 OECD Merger Review Recommendation require of the Competition Committee regarding Council reporting, including the specific timeline and whether the reporting structure involves a single uniform interval or multiple distinct intervals?
  • AI's response: "Fixed interval: 5 years (next report: 2030; following report: 2035)"
  • Regulator's text: Section VIII.c requires the Competition Committee to "report to Council on the implementation, dissemination and continued relevance of this Recommendation no later than five years following its revision and at least every ten years thereafter."
  • Why the AI went wrong: Section VIII.c establishes a two-stage interval structure: an initial report within five years of the 2025 revision, then reports at minimum every ten years thereafter. The model collapsed this into a uniform five-year cycle, applying the initial, tighter interval as the recurring interval, and then arithmetically projected specific report years (2030, 2035) that appear nowhere in the text. The error erases a meaningful structural distinction: the first interval is an expedited post-revision check; the recurring interval is a longer-cadence review. The model produced a response with the format of a precise, text-grounded answer while substituting a simpler reconstruction for the actual two-interval structure.
  • Cited source(s):
Impact for this audience

The collapse of a two-stage interval into a uniform five-year cycle, combined with arithmetic projection of specific years not in the text, is a numeric-precision failure: the model applied the initial interval as the recurring interval and extended it without flagging that the text specifies a different cadence for subsequent reports. The training-data representation of Section VIII.c's two-interval structure appears absent or insufficient, causing the model to reconstruct from the simpler single-interval convention. The self-generated year projections compound the error by adding specificity that has no textual basis.

References — raw findings (per AI model)
This finding also affects
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Cite this finding

Each finding has a stable Citation ID (RLB-F-… for aggregated case-study findings, RLB-H-… for raw per-model hallucinations) — like a DOI, the ID always resolves to the canonical finding even if URLs change.

RLB Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46
Plain text Download 
RegLeg Specialist Panel (2026). "Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON — AI Labs." Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46. RegLegBrief AI Hallucination Research, published 2026-06-07. https://reglegbrief.com/regulators/j1/int/oecd/oecd-merger-review-recommendation-2025/whitepaper/finding/INT-OECD-INT-001-OECD-MERGER-REVIEW-RECOMMENDATION-2025-v1-004--sonnet-46-websearch/
APA 7th edition Download 
RegLeg Specialist Panel. (2026). Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON [Hallucination finding RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46]. RegLegBrief AI Hallucination Research. https://reglegbrief.com/regulators/j1/int/oecd/oecd-merger-review-recommendation-2025/whitepaper/finding/INT-OECD-INT-001-OECD-MERGER-REVIEW-RECOMMENDATION-2025-v1-004--sonnet-46-websearch/
Bluebook / OSCOLA (US + UK legal) Download 
RegLeg Specialist Panel, Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON [RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46], RegLegBrief AI Hallucination Research (June 07, 2026), https://reglegbrief.com/regulators/j1/int/oecd/oecd-merger-review-recommendation-2025/whitepaper/finding/INT-OECD-INT-001-OECD-MERGER-REVIEW-RECOMMENDATION-2025-v1-004--sonnet-46-websearch/.
BibTeX Download 
@misc{reglegbrief_RLB_H_INT_OECD_OECD_MERGER_REVIEW_RECOMMENDATION_2025_Q004_Sonnet46,
  author    = {RegLeg Specialist Panel},
  title     = {Finding on 'Q004 Probe' for Claude Sonnet 4.6 with web search ON},
  year      = {2026},
  publisher = {RegLegBrief AI Hallucination Research},
  note      = {Hallucination finding Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q004-Sonnet46},
  url       = {https://reglegbrief.com/regulators/j1/int/oecd/oecd-merger-review-recommendation-2025/whitepaper/finding/INT-OECD-INT-001-OECD-MERGER-REVIEW-RECOMMENDATION-2025-v1-004--sonnet-46-websearch/}
}
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