US AISI ↔ UK AISI

1.0.0-rc.1 · Evidence cutoff 12 September 2026

Directly documented interface

Joint evaluation

Named evaluators conducted a shared exercise; not programme co-membership.

undirected. Undirected: a shared exercise, not a hierarchy.

Displayed claim → analysis (if present) → coded attributes → interface / instrument → atomic evidence → source version

Instrument and timeline

Instrument: Claude 3.5 Sonnet evaluation
Bindingness: No regulatory power inferred
Announced: Unknown
Observed by: 2024-11-19 · upper-bound
Effective period: Unknown → Unknown
Event: Conducted
Status at cutoff: historical event only
Last confirmation: 2024-11-19

Model-release dates conflict within the full report; report publication supplies conservative upper bound. No exact testing date asserted.

Undirected: a shared exercise, not a hierarchy.
Continuity through cutoff unresolved.

Status investigation

Checked 2026-09-12; assessed as of 2026-09-12. Last confirmation does not establish uninterrupted continuity.

amendments: unknown
expiry: unknown
termination: investigated within listed sources
restrictions: investigated within listed sources
succession: see succession.json
conflicts: Model-release dates conflict within the full report; report publication supplies conservative upper bound. No exact testing date asserted.

Search queries

"US AISI" "uk-aisi" joint evaluation 2026 amendment termination expiry status before:2026-09-13

Analytical assessment

No reviewed analytical conclusion is attached. This does not establish independence or absence of an institutional constraint.

Coded attributes

evaluation-capacity: substantial-access-constrained

Ability to design and execute a substantive assessment independently, conditional on access.

Evaluator × evaluation exercise or programme × date. Claude 3.5 Sonnet 2024 pre-deployment exercise; assessed 2024-11-19.

Completed independent tests establish capacity; explicit limited testing access narrows conclusions. Independently run assessments counters inference of provider-directed findings.

Supporting evidence: independent-tests access-limits . Counterevidence: independent-tests

Coding applies only to stated context and date, not a permanent institutional rank.

Published rubric anchors

absent: Affirmative evidence of no ability to perform this assessment.
nascent: Initial methods/team with no completed substantive assessment.
substantial-access-constrained: Completed independent assessment with documented access or time constraints materially limiting conclusions.
substantial-durable-access: Completed assessment and enforceable/reproducible access sufficient for the task over its defined period.

Unresolved when necessary evidence is missing or adjacent anchors cannot be distinguished. No numeric conversion. Absence requires affirmative remit or operational evidence, not missing sources.

evaluation-capacity: substantial-access-constrained

Ability to design and execute a substantive assessment independently, conditional on access.

Evaluator × evaluation exercise or programme × date. Claude 3.5 Sonnet 2024 pre-deployment exercise; assessed 2024-11-19.

Completed independent assessment plus explicit access/time limitation satisfies anchor. Not a statement of current CAISI resources.

Supporting evidence: independent-tests access-limits . Counterevidence: independent-tests

Coding applies only to stated context and date, not a permanent institutional rank.

Published rubric anchors

absent: Affirmative evidence of no ability to perform this assessment.
nascent: Initial methods/team with no completed substantive assessment.
substantial-access-constrained: Completed independent assessment with documented access or time constraints materially limiting conclusions.
substantial-durable-access: Completed assessment and enforceable/reproducible access sufficient for the task over its defined period.

Unresolved when necessary evidence is missing or adjacent anchors cannot be distinguished. No numeric conversion. Absence requires affirmative remit or operational evidence, not missing sources.

public-authority: limited

Institutionally authorized power to make decisions binding in the specified context.

Institution × legal/operational context × assessed date. February 2024 stated evaluation and advisory remit; assessed 2024-02-09.

Self-described supplementary evaluation and policy-advice remit supports advisory anchor. It does not code the powers of DSIT or UK government as a whole.

Supporting evidence: aisi-remit . Counterevidence:

Historical institutional remit. Later capacity, legislative changes or government powers require separate evidence. Limited denotes advisory remit here, not limited binding authority.

Published rubric anchors

absent: Affirmative remit excludes binding public decisions in this context.
limited: Advisory or delegated bounded public decisions.
substantial: Binding decisions over a significant but bounded function.
binding-operational: Documented binding decision and ability to carry it into operation in the defined function.

Unresolved when necessary evidence is missing or adjacent anchors cannot be distinguished. No numeric conversion. Absence requires affirmative remit or operational evidence, not missing sources.

information-access: unresolved

Ability to obtain non-public model information independently of provider consent.

Institution × information category × jurisdiction/date. Compulsion of access to non-public frontier checkpoints; assessed 2026-09-12.

A limited voluntary exercise cannot prove absence of all compulsory authority. No jurisdiction-wide classification from this evidence.

Supporting evidence: access-limits . Counterevidence: independent-tests

Coding applies only to stated context and date, not a permanent institutional rank.

Published rubric anchors

absent: Affirmative evidence excludes access in this context.
voluntary-provider-controlled: Access obtained through provider permission or negotiated instrument.
partial-compulsory: Specific compulsory information powers apply to some requested information.
broad-compulsory: Applicable legal powers reach the information needed for this defined task, subject to stated safeguards.

Unresolved when necessary evidence is missing or adjacent anchors cannot be distinguished. No numeric conversion. Absence requires affirmative remit or operational evidence, not missing sources.

Atomic evidence and exact sources

US AISI and UK AISI conducted a joint evaluation before the upgraded Claude 3.5 Sonnet release.

Source: Pre-deployment evaluation of upgraded Claude 3.5 Sonnet · NIST / US AISI and UK AISI
Version: 2025-03-20; retrieved 2026-09-12
Exact locator: Introduction; Overview of the Joint Safety Research & Testing Exercise, paragraphs 1–2
Limit: A completed exercise does not establish continuing access or regulatory authority.

Retrieved bytes SHA-256: eb91f397ed29e9e2684cd9dd518dea0b16fba6fbc5634d37cfc25297c78050b5

The exercise included biological and cyber capabilities; UK biological findings were not published in this summary.

Source: Pre-deployment evaluation of upgraded Claude 3.5 Sonnet · NIST / US AISI and UK AISI
Version: 2025-03-20; retrieved 2026-09-12
Exact locator: Overview, paragraph 2; Biological Capabilities, paragraph 2; Cyber Capabilities
Limit: Domain tags describe the exercise scope, not a finding about its effectiveness.

Retrieved bytes SHA-256: eb91f397ed29e9e2684cd9dd518dea0b16fba6fbc5634d37cfc25297c78050b5

The evaluation had a limited access and testing period.

Source: Claude 3.5 Sonnet joint testing report · US AISI / UK AISI
Version: 2024-11-19; retrieved 2026-09-12
Exact locator: Section 2.1, printed pages 1–2
Limit: Applies to this exercise; does not identify who caused the limits.

Retrieved bytes SHA-256: cee68f384975897e9ae8fd556baa9ebae9919fe08fe1e1abb363cbead7802903

The institutes each ran independent tests and worked together on methodology and interpretation of findings.

Source: Claude 3.5 Sonnet joint testing report · US AISI / UK AISI
Version: 2024-11-19; retrieved 2026-09-12
Exact locator: Section 1, printed page 1
Limit: Independence of tests does not establish durable model access.

Retrieved bytes SHA-256: cee68f384975897e9ae8fd556baa9ebae9919fe08fe1e1abb363cbead7802903

Section 2.2 says October 10; section 1 says October 22 for the model release.

Source: Claude 3.5 Sonnet joint testing report · US AISI / UK AISI
Version: 2024-11-19; retrieved 2026-09-12
Exact locator: Sections 1 and 2.2, printed pages 1–2
Limit: Retain discrepancy; use report publication as upper bound, not an exact evaluation date.

Retrieved bytes SHA-256: cee68f384975897e9ae8fd556baa9ebae9919fe08fe1e1abb363cbead7802903

In its February 2024 approach document, AISI describes itself as a secondary check rather than a regulator.

Source: AI Safety Institute approach to evaluations · DSIT / AI Safety Institute
Version: published-2024-02-09; retrieved 2026-09-12
Exact locator: A note on evaluations, final paragraph
Limit: Historical stated remit; not an assessment of every governmental power or all powers at September 2026.

Retrieved bytes SHA-256: 3cf1fee953c6819e009c82b58e5340b7e67737a824477c3ceced9ca636be981c

Supporting and conflicting evidence

Interface support: joint-evaluation, evaluation-domains, independent-tests. Counterevidence: release-date-conflict

Substantive review

evidence/joint-evaluation: approved · agent reviewer codex-research-checker · 2026-09-12

NIST explicitly describes the joint US/UK exercise on the upgraded Sonnet. The full report has inconsistent model-release dates; this proposition is not used as an exact testing date. Checked locator: Introduction; Overview of the Joint Safety Research & Testing Exercise, paragraphs 1–2. Source version: 2025-03-20.