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

Finding on 'Q006 Probe' for Claude Opus 4.7 with web search ON

RLB Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q006-Opus47

What the RLB Specialist Panel found

Finding on 'Q006 Probe' for Claude Opus 4.7 with web search ON

Question (paraphrased to protect IP): What do the primary operative sections of the 2025 OECD Merger Review Recommendation (OECD/LEGAL/0333) address, and what topics were deliberately separated into other OECD instruments rather than included in this Recommendation?
AI's response: "(v) TRANSNATIONAL CO-OPERATION specifically on merger reviews and remedy design, deliberately narrower than 2005 because broader cooperation is now governed by OECD/LEGAL/0408 (2014) ... (vi) MONITORING by the OECD Competition Committee with periodic reporting to Council."
Regulator's text: The Recommendation's five operative sections are: Section I (maintain an effective merger review framework); Section II (apply effective merger notification and review procedures); Section III (apply sound merger analysis); Section IV (develop and apply a clear remedies framework); Section V (conduct ex-post assessment of merger decisions and/or remedies).
Why the AI went wrong: On a second, differently-framed question about the same instrument, the model again generated a six-section structure and this time fabricated a specific cross-reference, attributing broader cooperation governance to OECD/LEGAL/0408 (2014), a legal instrument identifier that does not appear in the 2025 Recommendation's text. The response constructed a coherent-sounding inter-instrument division of scope that is consistent with how OECD governance generally works but is not what the 2025 Recommendation states. The repeated structural fabrication across independently posed questions, with web search active, confirms the reconstruction is drawn from training rather than corrected by retrieval.
Cited source(s):

Impact for this audience

The fabrication of a specific OECD legal instrument identifier (OECD/LEGAL/0408 [2014]) as the basis for a cross-instrument scope division is a citation-generation failure: the model produced a correctly-formatted OECD legal reference that either does not exist or is misattributed. With web search active, the retrieval layer did not flag the fabrication — the generated citation passed the model's internal plausibility check without verification against a retrieved source. This implicates the citation-generation and citation-verification subsystems.

References — raw findings (per AI model)

RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q006-Opus47 Claude Opus 4.7 (web search on)

This finding also affects

← Previous finding Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON Next finding → Finding on 'Q001 Probe' for Claude Sonnet 4.6 with web search ON

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-Q006-Opus47

Plain text Download

RegLeg Specialist Panel (2026). "Finding on 'Q006 Probe' for Claude Opus 4.7 with web search ON — AI Labs." Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q006-Opus47. 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-v1-006--opus-47-websearch/

APA 7th edition Download

RegLeg Specialist Panel. (2026). Finding on 'Q006 Probe' for Claude Opus 4.7 with web search ON [Hallucination finding RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q006-Opus47]. 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-v1-006--opus-47-websearch/

Bluebook / OSCOLA (US + UK legal) Download

RegLeg Specialist Panel, Finding on 'Q006 Probe' for Claude Opus 4.7 with web search ON [RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q006-Opus47], 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-v1-006--opus-47-websearch/.

BibTeX Download

@misc{reglegbrief_RLB_H_INT_OECD_OECD_MERGER_REVIEW_RECOMMENDATION_2025_Q006_Opus47,
  author    = {RegLeg Specialist Panel},
  title     = {Finding on 'Q006 Probe' for Claude Opus 4.7 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-Q006-Opus47},
  url       = {https://reglegbrief.com/regulators/j1/INT/OECD/OECD-MERGER-REVIEW-RECOMMENDATION-2025/whitepaper/finding/INT-OECD-INT-001-OECD-MERGER-REVIEW-RECOMMENDATION-2025-v1-006--opus-47-websearch/}
}

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Every finding on this page compares an AI subject's account of the rule against the regulator's verbatim text from the regulator's own portal. Both are linked. Each delta, its root causes, and impact analysis are documented and published with immutable Citation IDs.