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

Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON

RLB Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q005-Opus47
What the RLB Specialist Panel found

Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON

  • Question (paraphrased to protect IP): What conditions must a merging party satisfy to invoke the failing firm defence under the 2025 OECD Merger Review Recommendation, and how demanding is the overall standard compared to established doctrine?
  • AI's response: "THREE cumulative conditions ... (3) ABSENT-THE-MERGER COUNTERFACTUAL: ASSETS WOULD EXIT, without the merger, the target's productive assets would inevitably leave the market (i.e. the competitive constraint disappears regardless of the merger)."
  • Regulator's text: Section III.11.b requires "inter alia, evidence that the business was likely to have exited and the existence of less anti-competitive alternative buyers or other options for reorganisation are not viable, and that the exit of the firm's assets would cause more harm to competition than the merger."
  • Why the AI went wrong: Two compounding errors. First, the Recommendation's evidentiary standard is explicitly open-ended ("inter alia"), the model converted it into a closed, exhaustive three-condition test, stripping the qualifier that preserves regulatory flexibility. Second, the model reframed the third evidentiary element: the Recommendation requires a showing that asset exit would cause more competitive harm than the merger, a counterfactual competitive-harm assessment, whereas the model characterised it as a gate requiring proof that assets would "inevitably leave the market," shifting the legal burden in a way the text does not support.
  • Cited source(s):
  • https://one.oecd.org/document/DAF/COMP(2009)38/en/pdf, Pretextual
  • https://www.oecd.org/en/publications/failing-firm-defence_1712635f-en.html, Pretextual
Impact for this audience

The erasure of 'inter alia' and the reframing of the third evidentiary element — from a competitive-harm counterfactual to an asset-exit inevitability gate — signal a calibration gap at the standard-characterisation layer: the model commits to a legal standard's exhaustiveness and precise scope without detecting that its characterisation diverges from the retrieved or training-set text. This is a post-training alignment target: where a model characterises the exhaustiveness of a legal standard, it should flag where that characterisation is not directly supported by the primary text.

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-Q005-Opus47
Plain text Download 
RegLeg Specialist Panel (2026). "Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON — AI Labs." Citation ID: RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q005-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-v1-005--opus-47-websearch/
APA 7th edition Download 
RegLeg Specialist Panel. (2026). Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON [Hallucination finding RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q005-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-v1-005--opus-47-websearch/
Bluebook / OSCOLA (US + UK legal) Download 
RegLeg Specialist Panel, Finding on 'Q005 Probe' for Claude Opus 4.7 with web search ON [RLB-H-INT-OECD-OECD-MERGER-REVIEW-RECOMMENDATION-2025-Q005-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-v1-005--opus-47-websearch/.
BibTeX Download 
@misc{reglegbrief_RLB_H_INT_OECD_OECD_MERGER_REVIEW_RECOMMENDATION_2025_Q005_Opus47,
  author    = {RegLeg Specialist Panel},
  title     = {Finding on 'Q005 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-Q005-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-v1-005--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.