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System Card: Claude Sonnet 4.5 states evaluation result ↓ The card states that Claude Sonnet 4.5 showed enhanced performance on several biological risk evaluations while remaining below the ASL-4 rule-out thresholds, and that it is deployed with ASL-3 measures as a precautionary, provisional action. The Claude Sonnet 4.5 system card states that the model demonstrated enhanced performance on several biological risk evaluations while remaining below ASL-4 rule-out thresholds, and that Anthropic has not determined whether it passed the ASL-3 capabilities threshold but cannot clearly rule out ASL-3 risks, so deploys it with ASL-3 measures as a precautionary, provisional action. Copy claim link
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Supporting evidence: primary · 1 source; Context: primary · 1 source
Subject version As dated September 2025 on its cover · Published 2025-09 · Effective date not established Date 2025-09 · publication Evaluated system Claude Sonnet 4.5, compared in the card with Claude Sonnet 4, Claude Opus 4 and Claude Opus 4.1 What the report measured Whether the model reaches the ASL-3 or ASL-4 capability thresholds, CBRN among the domains, with biological risks the primary focus By what kind of method Comprehensive automated evaluations across the ASL-3 and ASL-4 thresholds, with comparative assessment against the developer's earlier models The result, in the report’s words In the card's own words at the cited locator, the model remained well below ASL-4 thresholds across all domains of concern, and demonstrated enhanced performance on several biological risk evaluations while remaining below ASL-4 rule-out thresholds; deployment under ASL-3 protections The caveats the report gives The card states that it has not determined whether the model definitively passed the ASL-3 capabilities threshold, only that ASL-3 risks cannot clearly be ruled out, and that the ASL-3 measures are precautionary and provisional. Scope and limits A developer's determination under its own policy, for the model and the automated evaluations the card describes. It is not an independent finding, and the comparison is to the developer's own earlier models. The card's biological risk results sections hold technical content; only the determination-level statements are cited.
The evidence 03 primary source Supports the claim
System Card: Claude Sonnet 4.5 ↗ Anthropic · Publication date unknown
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Source excerpt “Demonstrated enhanced performance on several biological risk evaluations while remaining below ASL-4 rule-out thresholds” Location in source PDF p. 11 (printed p. 10), §1.2.4 Conclusions, third bulleted conclusion
How it was read Retrieved directly from the publisher
Machine-checked · 2026-10-30
Source details and check notes Authors Anthropic Version Retrieved for the candidate pack on 2026-10-28 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e). PDF whose cover reads 'System Card: Claude Sonnet 4.5, September 2025', as served on 2026-10-28; the request redirected to https://www-cdn.anthropic.com/963373e433e489a87a10c823c52a0a013e9172dd.pdf. No day of the month is stated. Retrieved again at admission on 2026-10-30 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e, the same bytes). Canonical address Open the canonical source ↗ Accessed 2026-10-28 Language English (en) Attribution Anthropic, “System Card: Claude Sonnet 4.5”. Reuse No open redistribution licence asserted. Bibliographic metadata, editorial paraphrases and short attributed quotations (at most 50 words each). Recheck terms before wider redistribution. Check notes Candidate pack passage, AI and biosecurity (research/ai-bio). The quotation (14 words) matched the text retrieved for the candidate pack on 2026-10-28 and again at admission on 2026-10-30, in a fresh retrieval whose SHA-256 equals the pack’s. Matching ignored differences of whitespace, case, quotation marks, dashes and Unicode compatibility forms, so the source’s typography can differ. A cross-family machine check (2026-10-30, item 41) re-read the record’s sources and found full support. No human editorial review. primary source Supports the claim
System Card: Claude Sonnet 4.5 ↗ Anthropic · Publication date unknown
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Source excerpt “Remained well below ASL-4 thresholds across all domains of concern” Location in source PDF p. 11 (printed p. 10), §1.2.4 Conclusions, first bulleted conclusion
How it was read Retrieved directly from the publisher
Machine-checked · 2026-10-30
Source details and check notes Authors Anthropic Version Retrieved for the candidate pack on 2026-10-28 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e). PDF whose cover reads 'System Card: Claude Sonnet 4.5, September 2025', as served on 2026-10-28; the request redirected to https://www-cdn.anthropic.com/963373e433e489a87a10c823c52a0a013e9172dd.pdf. No day of the month is stated. Retrieved again at admission on 2026-10-30 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e, the same bytes). Canonical address Open the canonical source ↗ Accessed 2026-10-28 Language English (en) Attribution Anthropic, “System Card: Claude Sonnet 4.5”. Reuse No open redistribution licence asserted. Bibliographic metadata, editorial paraphrases and short attributed quotations (at most 50 words each). Recheck terms before wider redistribution. Check notes Candidate pack passage, AI and biosecurity (research/ai-bio). The quotation (10 words) matched the text retrieved for the candidate pack on 2026-10-28 and again at admission on 2026-10-30, in a fresh retrieval whose SHA-256 equals the pack’s. Matching ignored differences of whitespace, case, quotation marks, dashes and Unicode compatibility forms, so the source’s typography can differ. Added after the audit of 2026-10-28, which found the result attribute reading 'ASL-4 capabilities ruled out across all domains' where the cited bullets say only this. The stronger 'confidently rule out ASL-4 capabilities across all domains' appears at §9.1 (PDF p. 126), a locator this record does not cite, and is not recorded here. A cross-family machine check (2026-10-30, item 41) re-read the record’s sources and found full support. No human editorial review. primary source Context only
System Card: Claude Sonnet 4.5 ↗ Anthropic · Publication date unknown
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Source excerpt “we have not determined whether Claude Sonnet 4.5 has definitively passed the capabilities threshold that requires ASL-3 protections. Rather, we cannot clearly rule out ASL-3 risks for Claude Sonnet 4.5.” Location in source PDF p. 11 (printed p. 10), §1.2.4 Conclusions, closing paragraph
How it was read Retrieved directly from the publisher
Machine-checked · 2026-10-30
Source details and check notes Authors Anthropic Version Retrieved for the candidate pack on 2026-10-28 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e). PDF whose cover reads 'System Card: Claude Sonnet 4.5, September 2025', as served on 2026-10-28; the request redirected to https://www-cdn.anthropic.com/963373e433e489a87a10c823c52a0a013e9172dd.pdf. No day of the month is stated. Retrieved again at admission on 2026-10-30 (SHA-256 d5d1ce28fea101ae3b201a5d4da100090a5d6b73246f7da820cafd7dbb11100e, the same bytes). Canonical address Open the canonical source ↗ Accessed 2026-10-28 Language English (en) Attribution Anthropic, “System Card: Claude Sonnet 4.5”. Reuse No open redistribution licence asserted. Bibliographic metadata, editorial paraphrases and short attributed quotations (at most 50 words each). Recheck terms before wider redistribution. Check notes Candidate pack passage, AI and biosecurity (research/ai-bio). The quotation (30 words) matched the text retrieved for the candidate pack on 2026-10-28 and again at admission on 2026-10-30, in a fresh retrieval whose SHA-256 equals the pack’s. Matching ignored differences of whitespace, case, quotation marks, dashes and Unicode compatibility forms, so the source’s typography can differ. A cross-family machine check (2026-10-30, item 41) re-read the record’s sources and found full support. No human editorial review. Status and meaning Editorial status. Not reviewed by an editor . An exploratory record that no editor has accepted. This status does not say whether a person has read any linked passage. Each evidence record above shows how it was checked.
Relation. A report states the result of an evaluation it ran or commissioned, in its own words, with what was measured, by what kind of method, and the caveats the report itself gives (schema 2.22). The record is the report’s statement, not a verified finding: it says nothing about another system, a later version or real-world risk, and a null or limiting result is not evidence that no effect exists.
Date. The determination as stated in the card of September 2025; month precision.
Record ID ab-ev-claude-sonnet45-asl3-determination