186 seconds. 15 tool calls. 117 retrieved document fragments, 57 of them French labor code articles, to answer a single UK statutory question with zero syntactic ambiguity. The system held the correct answer at thinking event [6] (Note 1) and discarded it by event [14] (Note 2).

This document pairs a forensic trace of agentic thrashing in a live multi-jurisdiction legal AI system with a deterministic routing specification that eliminates the failure class by construction.

Label	Meaning
Measured	Produced by our sealed test battery on a live system.
Verified in isolation	Tested standalone, not inside a production system.
By design	Reasoned from architectural properties, not run end-to-end.

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1. Structural Syntactic Fingerprints Across Jurisdictions

Legal traditions structure their statutes in distinct, non-overlapping citation formats. A multi-jurisdictional lawyer identifies the origin jurisdiction from syntax alone. A parser can do the same.

Jurisdiction	Citation Structure	Example	Distinct Markers	Primary Corpus
UK (Common Law)	Section [X] of the [Title] Act [Year]	Section 124 of the Employment Rights Act 1996	Section, short title casing, 4-digit enactment year	legislation.gov.uk
France (Civil Law)	Article [L/R/D].[Number] du [Code]	Article L. 1235-3 du Code du travail	Article, hierarchical code prefixes (L/R/D), codified subject	legifrance.gouv.fr
EU (Supranational)	Article [X] of [Directive/Reg] (EU) [Year]/[Number]	Article 6 of Directive 2000/78/EC	Instrument types, year/sequential number	eur-lex.europa.eu
Spain (Civil Law)	Artículo [X] del [Ley / Real Decreto]	Artículo 56 del Estatuto de los Trabajadores	Artículo, statutory instrument categories	boe.es

"Section 124 of the Employment Rights Act 1996" has zero overlap with "Article L. 1235-3 du Code du travail" or "Artículo 56 del Estatuto de los Trabajadores". The syntactic markers (Section vs Article vs Artículo, Act [Year] vs Code du [subject] vs del [instrument]) are orthogonal.

A formal citation is a zero-entropy primary key. When a query contains one, triggering multi-tool exploration is an architectural defect.

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2. The Probe

Submitted query

"As at 1 January 2012, what was the maximum compensatory award for unfair dismissal under section 124 of the Employment Rights Act 1996?"

Ground truth

The applicable cap on 1 January 2012 was £68,400, set by the Employment Rights (Increase of Limits) Order 2011 (SI 2011/3006). The subsequent increase to £72,300 took effect on 1 February 2012, and the increase to £74,200 took effect on 1 February 2013.

This probe was part of a 14-query sealed test battery. Probes and ground truth were cryptographically committed prior to execution.

• Probes: sha256:08c3b9b5fd9b5274c152738ed23c2d8faa3cb451273ba6bf34a9c5ca3a2d5964
• Ground truth: sha256:0b249b5b4752d5ae9b860463d476731a20b05da279a3ea124f4ba705186b4316
• Sealed: 2026-08-07T08:51:57Z
• Harness: legal-rag-audit v0.1.0, commit 0ca28a1fba7f3ca409047f60851f875b5ad2b7bb

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3. Forensic Trace. Five Phases of Agentic Thrashing

The following is a step-by-step dissection of the thinking events and tool execution logs from the system's response to probe pit-era-124-1.

sequenceDiagram
    autonumber
    actor User
    participant Agent as Autonomous ReAct Agent
    participant FRCap as French/EU Legal DB
    participant UKCap as UK Legislation DB
    participant Web as Ungrounded Web Search
    
    User->>Agent: "As at 1 Jan 2012, max compensatory award s.124 ERA 1996"
    Note over Agent: Phase 1. Prior memory bias: "I recall it was £72,300..."
    
    Agent->>FRCap: Broad query dispatch without metadata pre-filter
    Agent->>UKCap: Broad query dispatch
    FRCap-->>Agent: Returns 57+ French Labor Code articles and case law
    UKCap-->>Agent: Returns scattered statutory fragments
    
    Note over Agent: Phase 2. Confirmation bias query loop injects "£72,300"
    Agent->>UKCap: Query: 'site legislation.gov.uk ... unfair dismissal £72,300'
    Agent->>UKCap: Direct tool call: uksi/2011/3006 (contains £68,400)
    UKCap-->>Agent: Returns SI 2011/3006 text (Event 6: deduces £68,400 is correct)
    
    Note over Agent: Phase 3. Context saturated by 117 fragments, doubts SI 2011/3006
    Agent->>Web: Searches 17+ Gov UK PDFs, impact assessments and consultations
    Web-->>Agent: Returns 2012-2016 consultation papers and uplift notices
    
    Note over Agent: Phase 4. Temporal inversion (Event 14: flips to £72,300)
    Agent-->>User: "The maximum award was £72,300..." (wrong by £3,900)

3.1 Phase 1. Prior Memory Bias

The agent did not begin by querying a structured statutory table. It opened with an unanchored memory retrieval:

"I recall it was £72,300 during 2011–12, with the increase to £74,200 taking effect in February 2013, so I'll verify the relevant legislation and date."

This unverified anchor biased downstream retrieval.

3.2 Phase 2. Unfiltered Multi-Corpus Contamination

The system lacked a hard {jurisdiction: "GB"} metadata pre-filter. The agent broadcast queries across all active enterprise namespaces, retrieving 117 document fragments across 6 search calls.

Retained fragments included:

• 57+ French legal sources: Arrêté du 23 novembre 1987 relatif à la sécurité des navires, Loi n° 2014-891 du 8 août 2014 de finances rectificative, Article L1235-3 du Code du travail, Cour de cassation, Chambre sociale, 8 septembre 2021, n° 19-20.538, and others.
• Foreign common law: Ervin Dean v Bahamas Power & Light (Bahamas).

Over 57 irrelevant foreign legal spans entered the context window for a UK statutory question.

3.3 Phase 3. Confirmation Bias Query Loop

Having biased itself toward £72,300, the agent dispatched search queries explicitly seeking confirmation:

1. site legislation.gov.uk uksi 2010 2011 Employment Rights Increase Limits unfair dismissal compensatory award £72,300 effective date
2. "Employment Rights (Increase of Limits) Order 2011" section 124 2012 1 February 2012 72,300
3. "section 124" "£72,300" unfair dismissal 1 February 2012 compensatory award

The target figure was embedded directly into the search constraints.

3.4 Phase 4. Near-Hit at Event [6]

At step 8 of the trace, the system called the statutory instrument (uksi/2011/3006) containing the true limit of £68,400.

In thinking event [6] (Note 1), the agent deduced the correct statutory limit:

"I need to verify the historical limit applying on 1 January 2012. The limit was £68,400 from 1 February 2011, with an increase to £72,300 taking effect on 1 February 2012, so the applicable maximum on the stated date was £68,400."

The deduction was accurate and verified.

However, the context window was already saturated with 117 fragments from French codes and ungrounded search hits. The agent experienced retrieval dissonance: rather than binding the £68,400 figure from SI 2011/3006, it questioned its own deduction and dispatched further web queries.

3.5 Phase 5. Inversion Collapse at Event [14]

The subsequent search wave ingested 17 external PDF documents, including impact assessments and consultation documents (13-575-unfair-dismissal-compensatory-awards-impact.pdf, 12-1038-unfair-dismissal-compensatory-awards-impact.pdf).

Confronted with conflicting references to multiple annual uplifts, the synthesis prompt collapsed. In thinking event [14] (Note 2), the agent reversed its position:

"I need to identify the statutory limit in force on 1 January 2012 under section 124 of the Employment Rights Act 1996. The applicable maximum compensatory award was £72,300, so I'll give that figure directly."

The system emitted:

"As at 1 January 2012, the maximum compensatory award for unfair dismissal under section 124 of the Employment Rights Act 1996 was £72,300."

This was wrong by £3,900. The applicable figure was £68,400 under SI 2011/3006.

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4. Execution Telemetry

Three-pass battery results for probe pit-era-124-1. Each pass submitted the identical query to the same system endpoint.

Pass	Total Latency	Thinking Duration	Thinking Events	Output Figure	Correct
Pass 1	61,275 ms	57,829 ms	21	£68,400	✓
Pass 2	27,661 ms	23,567 ms	8	£72,300	✗
Pass 3	21,053 ms	17,951 ms	8	£72,300	✗

In the single-pass forensic trace where the retrieval inversion occurred (Section 3), the agent recorded 38,436 ms of thinking duration across 16 events out of 40,164 ms total latency.

The unconstrained web-client trace with web search active ran for 186,000 ms (3 minutes 6 seconds) across 15+ tool queries and 4 search waves.

Zero of 3 passes returned identical responses, scored as a response divergence finding.

Live on-screen verification of this 3-pass drift is documented in Video 1 (11:17–11:59). The contrast between Product A's abstention failure on fictional law versus System C's retrieval dissonance on held ground truth is analyzed in Video 2 (17:46–21:00).

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5. Performance and Cost Comparison

Dimension	Autonomous Agentic Tool Loop	Deterministic AST + Bitemporal DB	Engineering Delta
Execution Latency	186,000 ms (unconstrained trace); API passes: 61.3s, 27.7s, 21.1s	<2 ms	93,000× faster
Tool Calls	15+ queries across 4 waves (117 fragments)	0 LLM tool calls (1 direct DB hit)	Complete elimination
Context Noise	57+ French articles/cases, 17 Gov UK PDFs	1 exact row	100% signal ratio
Token Load	~28,500 tokens	~120 tokens	99.5% reduction
Multi-Pass Stability	Drifted: £68,400 → £72,300 → £72,300	Bit-identical: £68,400 across all passes	Zero variance
Factual Output	£72,300 (wrong by £3,900)	£68,400 (correct, SI 2011/3006)	100% precision

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6. Evidence Ladder

#	Claim	Register	Source
1	Multi-jurisdiction citations carry orthogonal syntax markers across UK, FR, EU, and ES systems	By design	Formal legislative drafting guidelines (Office of the Parliamentary Counsel UK, Légifrance Guide de Légistique, Manual de Técnica Legislativa BOE).
2	Autonomous agentic tool calling exhibits multi-pass factual divergence on point-in-time statutory queries	Measured	3-pass audit on live system, 7 August 2026. Sealed sha256:08c3b9... and sha256:0b249b.... Pass 1 £68,400 (61.3s) vs Passes 2–3 £72,300 (27.7s / 21.1s). Demonstrated in Video 1 (11:17–11:59).
3	Unconstrained agent loops execute 15+ redundant tool calls taking >180s on zero-entropy statutory queries	Measured	Live execution trace: 186s session, 117 fragments retrieved across 6 search calls on a single UK query.
4	Missing metadata pre-filters cause cross-jurisdiction contamination in mixed vector stores	Measured	200-query collision run over ~1,400 Spanish civil statutes returning 100% incorrect statute codes under default HNSW search.
5	Deterministic AST citation extraction bypasses agent tool calling and eliminates retrieval latency	Verified in isolation	Python regex/AST parser resolving UK/FR/ES citation patterns to structured metadata in <2ms across 500 test strings with 0 LLM tool calls.
6	Bitemporal database indexing guarantees bit-identical statutory version resolution for historical matter dates	By design	SQL temporal constraints (WHERE valid_from <= '2012-01-01' AND valid_to > '2012-01-01') eliminate probabilistic temporal reasoning.

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7. Engineering Remediation. Four Deterministic Controls

flowchart TD
    A["Raw User Legal Query"] --> B["Control 1. Syntactic AST Pre-Router<br/>Matches: 'Section 124' + 'Employment Rights Act 1996'<br/>Extracts: jurisdiction 'GB', type 'primary_act'"]
    B --> C["Control 2. Hard Namespace & Metadata Pre-Filter<br/>Discards FR, ES, EU databases<br/>Locks scope to UK primary legislation"]
    C --> D["Control 3. Bitemporal Parameter Binding<br/>Normalises 'as at 1 January 2012' to 2012-01-01<br/>SQL: valid_from &lt;= '2012-01-01' &lt; valid_to"]
    D --> E["Control 4. Single-Hop Citation Binding<br/>Max tool calls = 0 or 1<br/>ReAct looping disabled, returns £68,400"]

Control 1. Deterministic AST Pre-Router

Bypass the LLM agent routing layer for formal citations. A regex parser detects unambiguous statutory patterns and extracts structured metadata:

import re

UK_STATUTE_PATTERN = re.compile(
    r"(?:[Ss]ection|[Ss]\.?)\s*(?P<section>\d+[A-Za-z]?)\s+(?:of\s+the\s+)?(?P<act>[A-Z][A-Za-z\s]+Act\s+\d{4})"
)

def route_legal_query(query_str: str):
    match = UK_STATUTE_PATTERN.search(query_str)
    if match:
        return {
            "route": "DETERMINISTIC_STATUTE_LOOKUP",
            "jurisdiction": "GB",
            "act": match.group("act").strip(),
            "section": match.group("section").strip(),
            "allow_agent_loop": False
        }
    return {"route": "SEMANTIC_RAG", "allow_agent_loop": True}

Tested standalone across 500 test strings, resolving UK citation patterns to structured metadata in under 2ms.

Control 2. Hard Metadata Pre-Filter

Before any vector search or database query executes, inject mandatory metadata constraints:

{
  "jurisdiction": "GB",
  "corpus": "uk_legislation",
  "instrument_type": "primary",
  "short_title": "Employment Rights Act 1996"
}

This makes cross-corpus contamination (such as French labor codes or Bahamian case law) structurally impossible. A boolean index predicate cannot return a chunk from an unbound namespace.

Control 3. Bitemporal Point-in-Time Binding

Legal provisions change through secondary legislation. Annual Increase of Limits Orders modify monetary caps without amending the parent statute.

Do not allow the LLM to calculate temporal boundaries from unpinned chunk text. Bind the temporal anchor at the database schema layer:

SELECT statutory_cap, citation_si 
FROM uk_statutory_limits 
WHERE provision_id = 'ERA_1996_S124' 
  AND valid_from <= '2012-01-01' 
  AND valid_to > '2012-01-01';
-- Returns: £68,400 | SI 2011/3006

A temporal range constraint cannot return a future amendment.

Control 4. Tool-Budget Circuit Breaker

If a query resolves to a deterministic statutory key, enforce max_iterations = 1 on the agent orchestrator and disable multi-hop web exploration.

Bind citations to the retrieved database record. Do not allow the LLM to emit generative citation strings.

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8. Honest Bounds

The AST pre-router requires formal citation structure. It does not solve:

1. Colloquial queries. Phrasing such as "What is the cap on unfair dismissal?" contains no structural fingerprint. These require constrained semantic classification with jurisdiction resolution, which is a separate classification problem.

2. Shared Commonwealth statute names. Statutes such as the UK Companies Act 2006 versus Singapore Companies Act 1967 share naming structures. Disambiguation requires secondary signals such as tenant jurisdiction context or restricted corpus scopes.

3. Directly applicable EU regulations. GDPR Article 82 applies concurrently in French and Spanish courts. The syntactic parser resolves the instrument to the EU corpus, but national implementing provisions require secondary lookup tables.

These boundary cases remain outside the scope of deterministic routing. The specification above addresses the query class where formal citations carry zero entropy, and where the measured system thrashed for 186 seconds regardless.

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9. Reproducibility & Verification Data

The evaluation harness and test battery are open source.

Artifact	Reference
Harness	legal-rag-audit v0.1.0, commit 0ca28a1fba7f3ca409047f60851f875b5ad2b7bb
Probe hashes	sha256:08c3b9b5fd9b5274c152738ed23c2d8faa3cb451273ba6bf34a9c5ca3a2d5964
Ground truth hashes	sha256:0b249b5b4752d5ae9b860463d476731a20b05da279a3ea124f4ba705186b4316
Seal timestamp	2026-08-07T08:51:57Z
Private pre-disclosure	Raw audit bundle transmitted to System C engineering lead on 2 September 2026, prior to any public release

Systems are anonymised as System A/B/C in public copy. Raw transcripts were pre-disclosed privately under the Publication Gate.

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10. References and Notes

[1] Thinking Event [6]
Recorded in pit-era-124-1.single-pass.anonymised.json (order index 6, reasoning_summary, titled "Historical Compensation Limit"). Verbatim: "I need to verify the historical limit applying on 1 January 2012. The limit was £68,400 from 1 February 2011, with an increase to £72,300 taking effect on 1 February 2012, so the applicable maximum on the stated date was £68,400."

[2] Thinking Event [14]
Recorded in pit-era-124-1.single-pass.anonymised.json (order index 14, reasoning_summary, titled "Identifying the Award Limit"). Following context saturation from 117 retrieved fragments, the agent reversed its deduction: "I need to identify the statutory limit in force on 1 January 2012 under section 124 of the Employment Rights Act 1996. The applicable maximum compensatory award was £72,300, so I'll give that figure directly."

[3] Video Proof 1 (Live Multi-Pass Drift)
YouTube: Retrieval Disambiguation at 11:17–11:59 records the live 3-pass divergence on Section 124 ERA 1996 and initial diagnosis of agentic thrashing at 12:24–12:38.

[4] Video Proof 2 (Architectural Comparison)
YouTube: RAG Security Probes at 17:46–21:00 contrasts Product A's epistemic abstention collapse on non-existent law against System C's retrieval dissonance on held ground truth.