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EY Canada AI hallucination report: QA governance for AI deliverables in custom development 2026

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On May 30, 2026, EY Canada published a cybersecurity report and most citations were hallucinated rose to the top of Hacker News. An investigation by GPTZero revealed that more than half of the citations (27 out of 51) in the annual cybersecurity report released by EY Canada (a Big Four firm) were AI hallucinations (non-existent research papers, URLs, and statistics). While EY initially responded by deleting the report, the issue was widely covered across business media as brand damage for an audit firm.

From the perspective of supporting AI adoption, content generation, and proposal materials for mid-sized enterprises through custom development, this signifies that organizations solely pursuing "writing faster with AI" have entered an era where lacking governance—namely, "publishing AI outputs without running them through an internal verification workflow"—causes catastrophic brand damage. Connecting this with the input-side governance in OpenAI Privacy Filter & Trusted Access AI Governance (GH Media), the test automation in Automating QA with Playwright × AI (GH Media), and the prompt architecture in Custom Anthropic XML Prompt Structure Development (GH Media), we organize the key considerations when assembling "AI deliverable QA governance" for custom development engagements. Note that "provenance and digital watermarking (SynthID / C2PA) to prove whether content is AI-generated" was addressed in Custom Development: Protecting AI Content Trust with SynthID and C2PA (GH Media); this article focuses on its counterpart: "how to verify the factual accuracy of outputs."

Why “AI deliverable QA governance is a turning point”

DimensionConventional QA (centered on human writing)QA in the AI era (centered on AI generation)
Verification targetsText / numbers / logic+ Citations / URLs / statistics / regulations
Types of errorsTypos / transcription errors / logical inconsistencies+ Hallucinations (non-existent sources)
Detection methodsVisual inspection by proofreaders+ LLM × secondary LLM × URL existence verification
Locus of responsibilityAuthors+ Prompt designers + review infrastructure
Approval flowsEditorial → Legal+ AI fact-checking → Editorial → Legal
Post-publication auditingCorrection notices+ Audit logs + prompt reproducibility
Brand riskMinorSevere (reverberates across the industry)
Target deliverablesArticles / reports+ Proposals / legal documents / IR / audit materials

In short, AI deliverable QA demands a structural shift from “proofreading human writing” to “protecting AI-generated output through facts and auditability.”

Three structural changes beneficial to custom development projects

Structure 1: From “manual proofreading” to “LLM × verification LLM × external APIs”

Even if marketing, PR, and sales planning teams in mid-market companies have adopted workflows to write faster using ChatGPT, fact-checking still relies on manual proofreading. In our custom engagements, we incorporate a secondary verification LLM distinct from the drafting LLM, URL existence checks, and cross-referencing against academic databases and official statistical APIs directly into the pre-publication pipeline. This represents the content counterpart to the automated QA using AI covered in Automating QA with Playwright and AI (GH Media).

Structure 2: From “author responsibility” to “prompt + audit log accountability”

The EY incident illustrated that accountability can no longer rest solely on “the author used AI.” In our custom solutions, we ensure that prompts, responses, verification results, and approvers are encrypted and retained for set retention periods, making outputs fully reproducible when issues arise. This is the output audit counterpart to the input governance discussed in OpenAI Privacy Filter Governance (GH Media).

Structure 3: From “marketing and PR only” to “deliverables across all departments”

QA governance is essential not only for articles, but also for proposals, estimates, legal documents, and IR materials. In our engagements, we establish variable verification rigors based on departmental risk levels, applying maximum rigor to legal, IR, and audit materials, while maintaining lightweight workflows for internal study materials. This represents the approval flow counterpart to the structured prompts covered in Anthropic XML Prompt Structure for Clients (GH Media).

The 5 phases of assembling “AI deliverable QA governance”

Phase 1: Current state assessment (2 weeks)

  • Inventory of AI-utilizing departments and tools
  • Classification of public and externally submitted deliverables
  • History of past near-misses and corrections
  • Existing approval flows / legal reviews
  • Brand risk scoring
  • Departmental verification rigor matrix

Phase 2: Governance design (2–3 weeks)

  • Deliverable risk levels (Red / Yellow / Green)
  • Verification workflows (automated / semi-automated / manual)
  • Mandatory checklist items (citations / statistics / regulations / proper nouns)
  • Audit log retention + access controls
  • Approvers and exception handling procedures
  • Governance KPIs

Phase 3: Technical implementation (3–5 weeks)

  • Verification LLM pipeline (OpenAI / Anthropic / Bedrock)
  • URL existence checks (HEAD requests + Wayback)
  • Academic / statistical API integrations (Semantic Scholar / Crossref / e-Stat)
  • Legal database integrations (e-Gov / Westlaw / LexisNexis, etc.)
  • Workflow foundations (Notion / Asana / Jira / in-house)
  • Dashboards (Grafana / Datadog / Looker)

Phase 4: Pilot rollout (2–3 weeks)

  • Commencing operations in 1–2 departments
  • Verification pass rate measurement
  • False positive and false negative triage
  • Training + runbook distribution
  • KPI measurement + refinement

Phase 5: Monthly operational reviews (ongoing)

  • Verification pass / rejection statistics
  • Addition of novel error patterns
  • Evaluation of LLM vendor transitions
  • Brand risk incident reviews
  • Semi-annual standards revision

Standard technology stack set for custom development

LayerRecommended technologyAlternative
Drafting LLMGPT-5.5 / Claude Opus 4.X / Gemini 3.5DeepSeek / Llama
Verification LLMHigher-tier model from an alternative vendorDifferent generation from the same vendor
URL verificationIn-house + Wayback Machine APILinkChecker
Academic / statisticsSemantic Scholar / Crossref / e-StatOpenAlex
Legal databasese-Gov / Daiichi Hoki / WestlawLexisNexis
WorkflowNotion / Asana / Linear / in-houseJira
Audit LoggingOpenTelemetry + S3 / GCS + encryptionDatadog Logs
SIEMMicrosoft Sentinel / SplunkSumo Logic

Which projects need this and which do not

Projects requiring thisProjects not requiring this
Generating externally published content with AIInternal memos only
Using AI for proposals / IR / audit materialsChit-chat bot
Audit requirements (ISO 27001 / SOC 2 / J-SOX)Not subject to auditing
Industries with significant brand damage risksMinimal impact scope
Drafting legal / regulatory compliance documents with AIUnregulated areas

Six clauses to include in client contracts

ClauseDetailsWhat the client should verify
Target deliverablesDepartment-by-department coverage and exclusionsHandling out-of-scope items
Risk levelRed / yellow / green judgment criteriaBusiness-specific factors
Mandatory verification itemsCitations / statistics / laws and regulations / proper nounsIndustry-specific checks
Audit log retentionRetention period + encryption + access controlRegulatory requirements
Handover Upon Project CompletionPrompts / verification rules / logsInternal operational continuity
Incident operationsPost-publication retractions and PR coordinationEscalation thresholds

Client ROI estimate (assuming 400 monthly deliverables across 6 departments)

ItemCurrent state (manual proofreading only)After implementing QA governanceDifference
Monthly hallucination oversight count12 incidents1 incident-11 incidents
Post-publication corrections / retractions per year8 cases1 incident-7 incidents
Proofreading workload (monthly)200 hours60 hours-140 hours
Audit support workload (annual)240 hours80 hours-160 hours
Brand damage risk (annual)Projected 1 major + 3 moderate incidentsProjected 1 moderate incident-80% risk
Annual benefitWorkload reduction equivalent to approximately 18 million yen + brand protection

Equivalent to an annual workload reduction of 14 million yen + correction handling cost savings at an hourly rate of 8,000 yen. When evaluating return on investment, be sure to include brand risk avoidance (preventing corrections, retractions, and PR responses) as the greatest benefit alongside these workload cost savings in your assessment criteria.

Five common pitfalls

Pitfall 1: Using the same LLM for drafting and verification

Having the same model self-verify frequently leads to cases where the same hallucination is judged as "correct." As a golden rule, verify using a higher-tier model from a different vendor.

Pitfall 2: Checking only HTTP 200 status for URLs

A URL existing and it substantiating the stated content are entirely different matters. Delve deeper with Wayback Machine / academic databases / content snippet matching.

Pitfall 3: Overcomplicating workflows

Applying the verification pipeline at maximum rigor to all deliverables leads to on-site teams creating workarounds. A design that adjusts rigor based on risk levels is essential.

Pitfall 4: Failing to capture audit logs

If you cannot reproduce "which prompt produced which response" when an issue occurs, root cause investigation and recurrence prevention become impossible. Operate with encryption + time-limited retention.

Pitfall 5: Failing to involve legal, IR, and PR

QA governance is not merely a technical challenge; it encompasses operations up to post-publication retractions, correction announcements, and stakeholder notifications. Involving legal, IR, and PR during the initial setup is mandatory.

90-day action plan

WeekAction
Week 1〜2Inventory + risk-level design + near-miss collection
Week 3〜5Governance design + KPIs + legal / IR / PR alignment
Week 6〜10Verification pipeline construction + API integration + workflows
Week 11〜12Pilot department rollout + training + KPI measurement
Week 12Company-wide rollout + runbook preparation
Week 13Initial monthly review + ROI dashboard

Summary — Moving from "writing faster with AI" to "governance that protects AI deliverables"

EY Canada's AI hallucination report symbolized an era where even a Big Four firm suffered catastrophic brand damage by neglecting AI deliverable governance. From the perspective of supporting AI adoption for mid-sized enterprises through custom development, "AI deliverable QA governance"—integrating drafting LLMs, verification LLMs, external APIs, workflows, and audit logs—will become an indispensable discussion going forward.

If you have concerns such as "citations in our AI-written proposal were fabricated," "we almost published hallucinated statistics in a press release," or "our pre-publication verification workflow for external content is inadequate," please feel free to reach out via our contact form. Because the scope of verification pipeline implementation and targeted departments vary greatly by enterprise, we provide individualized estimates after reviewing your current AI usage.

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Kakeru Suzuki

Fascinated by the possibilities of technology, has had a deep interest in programming and digital art since student days

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