MES Access Review

This topic is part of the SG Systems Global regulatory & operations guide library.

MES Access Review: periodic role/permission audit for least privilege, SoD, and defensible audit trails.

Updated Jan 2026 • mes access review, user access management, role based access, segregation of duties, audit trail, data integrity • Cross-industry

MES Access Review is the formal, periodic process of verifying that every user, role, and account with access to the Manufacturing Execution System (MES) still needs that access, has the right level of access, and is separated from incompatible duties. It is the difference between “we think permissions are okay” and “we can prove permissions are controlled.”

Most plants don’t suffer from a total absence of access controls. They suffer from access drift: users change jobs, teams cover shifts, contractors stay on longer than expected, supervisors accumulate permissions “temporarily,” and integrations get created with broad service accounts because it’s faster. Six months later, nobody can confidently explain who can do what—or why. That’s how you end up with silent bypass of controls, weak attribution, and ugly investigations that burn time and credibility.

In an execution-focused MES, access is not an IT convenience feature. It is a core manufacturing control. If a person (or service account) can complete steps, reverse transactions, override gates, or approve dispositions without governance, the system stops being an enforcement layer and becomes a record-keeping tool with holes. And holes are where recurring deviations, “mystery” inventory variances, and defensibility failures come from.

“Access reviews aren’t paperwork. They’re how you keep your MES from becoming bypassable.”

1) What MES access review actually means

A MES access review is not just “look at a user list.” It is a control activity that answers four questions for each identity:

• Should this identity exist? (active employee/contractor/system; not terminated; not expired)
• Is the access justified? (job role, site/line assignment, current responsibilities)
• Is the access limited? (least privilege; no unnecessary admin; no broad cross-site rights)
• Is the access compatible with duties? (no prohibited combinations that break SoD)

For an MES specifically, access review must cover the permissions that can change execution truth: batch state transitions, step completion, consumption and yield postings, holds/releases, exception dispositions, and approvals. These are the actions that define manufacturing execution integrity.

Access reviews are closely tied to:

• Access Provisioning (how access is granted and removed)
• Role-Based Access and User Access Management (how permissions are structured)
• Segregation of Duties in MES (who can execute vs verify vs approve)
• Audit Trails and Data Integrity (how you prove the system is controlled)

If your review doesn’t produce a defensible record of decisions (keep/remove/modify) and approvals, it isn’t a control activity. It’s a meeting.

2) Why access drift destroys execution integrity

Access drift creates two types of harm: silent bypass and weak attribution.

Silent bypass happens when someone can do things they shouldn’t be able to do. In an execution system, that can mean:

• overriding a gate that should block execution (in-process compliance enforcement)
• approving their own work (SoD failure)
• closing steps without required evidence (step-level enforcement failure)
• changing master data or recipes outside change control (change control failure)

Weak attribution happens when “who did it” is not reliable—typically due to shared accounts, shared terminals, or service accounts that look like people. That undermines audit readiness and makes root cause analysis guessy instead of evidence-driven (see RCA).

Both issues show up later as downstream pain: repeated deviations, inventory variance, yield disputes, and QA review that slows releases because the evidence chain is not trustworthy.

3) Outcomes: what “good” looks like

A mature MES access review program produces outcomes you can actually measure:

Operationally, “good” means the routine execution path is locked down and fast, while exceptions require explicit approvals and leave strong evidence. That supports review by exception because QA can trust the controls that produced the record.

4) Scope: identities, roles, stations, and integrations

Scope is where access reviews often get watered down. A real MES access review covers every identity that can influence execution truth:

In many organizations, access review also includes connected systems that share governance with MES, such as eQMS, document control systems, and WMS. But the MES review should, at minimum, cover the MES itself and any identity that can push state changes into it.

5) Cadence: how often (and what triggers off-cycle review)

Cadence should be risk-based. The mistake is to pick one frequency for everyone. A better approach tiers by impact:

Off-cycle triggers are just as important as the calendar:

• organizational changes (new lines, new shifts, mergers, site expansions)
• significant deviations or integrity events (indicates potential bypass risk)
• major MES configuration releases or integrations (change introduces drift)
• new product introduction or new risk profile (see NPI)

6) Inputs: the minimum data you need

Don’t start the review without the right inputs. Otherwise, you end up arguing about opinions instead of checking facts.

• Current user list (active/inactive status, last login, site/line assignment)
• Role definitions (what each role can do and what it cannot do)
• Role-to-user mapping (who has which roles)
• Permission details for privileged functions (overrides, admin, approvals)
• Service account list (purpose, owner, endpoints used, scopes)
• HR/contractor roster for employment/engagement status
• Training/qualification matrix for execution eligibility where training gates apply (see training-gated execution)
• Change control records for access model changes (see change control and revision control)

Where auditability matters, tie records to document control so your review outputs aren’t “lost in email.”

7) Step-by-step access review workflow

Access review should be a repeatable workflow with defined roles and outputs. Below is a practical template that scales across sites.

8) Role model design (RBAC) that makes reviews sane

If your MES permissions are assigned as one-off custom entitlements per person, access review becomes nearly impossible. You end up reviewing hundreds of unique permission sets and nobody can explain why they exist.

A review-friendly design uses:

• Role-based access as the standard (RBAC).
• Role constrained execution for high-risk steps (role constrained execution).
• Operator authorization matrix mapping roles to step types and areas (operator authorization matrix).
• Credential-based execution control where credentials/qualifications gate actions (credential-based execution control).

The core objective is to make “normal” access assignment simple and tight, and to make “exceptions” rare, visible, and time-limited. This also supports training-gated execution because training gating only works if roles align to actual job functions.

Also: keep role names operationally meaningful. “MES_User_47” is not meaningful. “Packaging Operator – Line 3” is.

9) Segregation of duties checks for MES

Segregation of duties in MES is about preventing a single person (or identity) from executing and then approving/validating their own execution in ways that would defeat controls.

Common SoD patterns in MES include:

• Execute vs Verify: steps requiring independent verification should not be self-verified (see dual verification and dual control operations).
• Create vs Approve: a person who creates an exception/disposition should not approve it alone.
• Configure vs Execute: system configurators should not routinely execute production steps with the same identity.
• Override vs Release: override authority should be separate from final disposition/release where feasible.

SoD also intersects with electronic signatures and the meaning of sign-off. If approvals are meaningful evidence, then identities must be controlled and attributable.

10) Privileged access: admin, overrides, and “break-glass”

Privileged access is where many access review programs fail because teams treat admin roles as “IT only.” In MES, privileged access often includes the ability to:

• change master data or configuration that defines execution rules
• modify workflow states (batch state transitions)
• create or delete critical records
• disable enforcement controls
• apply overrides that should be rare and auditable

A strong model distinguishes:

• System administrators (platform operations)
• Configuration owners (controlled changes to execution logic)
• Override approvers (rare, controlled exceptions)
• Auditors/reviewers (read-only access for review)

When break-glass access exists, treat it as an exception workflow: time-limited, logged, reviewed, and linked to incident/change records. If break-glass becomes routine, it is a signal that your normal role model or process design is broken.

11) Temporary access and time-bound elevation

Temporary access is legitimate in manufacturing. Emergencies happen. Coverage happens. But “temporary” must be engineered so it doesn’t become permanent drift.

Minimum controls for temporary access:

• Documented justification (why needed, what scope, what duration)
• Time-bound expiry (automatic revocation; no manual cleanup required)
• Approvals (role owner + quality owner where risk justifies)
• Post-event review (confirm it expired; check for any misuse)

In MES, the scariest temporary access is “temporary admin.” If you must do it, time-box it aggressively and require a second-person approval for major actions.

12) Service accounts and integration identities

Service accounts are the #1 hidden risk in MES access governance. They can touch thousands of transactions quickly, and they often have broad rights “so the integration won’t break.” That’s not a control posture. That’s a fragility posture.

For each service account, an access review should answer:

• What system uses it? (ERP, WMS, LIMS, eQMS, custom apps)
• What endpoints/actions does it need? Read-only vs state-changing actions
• Who owns it? A named accountable owner (not “IT”)
• What data scope is allowed? Site/line/product scope constraints
• How is it monitored? Logs reviewed for unusual activity

Service accounts should never be used to emulate operator execution. If an interface must post execution outcomes, ensure it cannot bypass the execution rules. That is the point of execution-level enforcement.

Also: if you allow a service account to “approve” records or apply final dispositions, you’ve created automated self-approval. That breaks SoD and undermines the meaning of approvals.

13) Evidence pack, approvals, and record retention

The deliverable of an access review is an evidence pack. If you can’t produce this quickly during an audit or investigation, the review doesn’t exist in any meaningful way.

A practical evidence pack includes:

• review period and scope (which systems/sites/roles included)
• exported access listing (users, roles, permissions, service accounts)
• SoD conflict report and resolution notes
• list of removals/modifications with approvals
• verification evidence that changes were applied
• exceptions: temporary access grants, break-glass events, and closures
• retention reference (where stored, retention period)

Retention and archiving should align to your internal requirements and the integrity expectations of record retention and archival. Put the evidence under controlled storage—ideally governed by document control systems where applicable.

Access review evidence also supports internal audits. If internal audit can’t trace the review end-to-end, external auditors won’t be impressed either.

14) KPIs and trending (how you prove it’s working)

Access review programs collapse when they aren’t measured. Measurement turns “compliance activity” into “operational control.”

Also trend causes: Are conflicts mostly caused by coverage? by training gaps? by poor role design? This is where you connect access review to system improvement instead of repeating the same cleanup every quarter.

15) Automation without losing control

Automation is good—until it creates bypass. The right way to automate access review is to automate visibility and workflow, not to automate uncontrolled permissions.

Safe automation patterns:

• Automated reporting: scheduled exports of role membership, privileged access, and dormant accounts.
• Automated alerts: flag accounts that haven’t logged in; flag temporary access nearing expiry; flag SoD conflicts on assignment.
• Workflow routing: route approvals through controlled approval workflows.
• Training linkage: align roles to training via a training matrix, supporting training gates where used.

Risky automation patterns:

• auto-assigning broad roles “based on department” with no approval
• service accounts that self-elevate
• silent role changes without evidence

If your MES is validated or treated as controlled, automation changes must be governed under CSV and risk-based practices like GAMP 5, with change governance via change control.

16) Common failure modes (and how to stop them)

• Failure: shared accounts “for convenience.”
  Fix: enforce named users wherever approvals or execution truth is captured; use station controls that still require user sign-on.
• Failure: supervisors accumulate every permission.
  Fix: design supervisor roles tightly; force temporary elevation for rare tasks; review supervisor roles quarterly.
• Failure: service accounts have admin rights.
  Fix: split integrations into least-privilege accounts by function; remove approval/override capabilities from service identities.
• Failure: access review is a spreadsheet exercise with no remediation.
  Fix: require closure evidence: a “before/after” access listing and change confirmation.
• Failure: SoD is documented but not enforced.
  Fix: enforce SoD constraints in MES roles and workflows (see SoD in MES and dual control).
• Failure: changes happen outside change control.
  Fix: treat role model updates as controlled changes with revision control and MOC.

17) How access review supports execution-oriented MES

An execution-oriented MES depends on real gates: the system must be able to block wrong actions, require dispositions, and enforce who can do what. Access review is how you keep those gates real over time.

Specifically, access review supports:

• Execution gates: roles determine who can transition states and who can override execution-level enforcement.
• Controlled sign-off: verification and approvals remain meaningful (see electronic operator sign-off and electronic signatures).
• Audit trail credibility: audit logs are attributable and defensible (audit trail, data integrity).
• Review by exception: exceptions stand out and can’t be “approved away” casually (review by exception).

If you want the MES to reliably enforce training gates, calibration gates, or equipment eligibility (equipment execution eligibility), then access and roles must be tight. Otherwise users will be tempted to “work around the system” with a more privileged login—especially during high pressure.

18) Cross-industry examples

Access review is universal, but the highest-risk permissions vary by industry and operating model:

• Pharmaceutical manufacturing: approval rights, batch record actions, and roles tied to controlled execution and quality disposition are usually high focus (see pharmaceutical manufacturing).
• Medical device manufacturing: document-controlled work instructions and traceability approvals often drive SoD design (see medical device manufacturing).
• Food processing: lot status, holds, and traceability controls can be the critical access boundary (see food processing).
• Produce packing: label/traceability controls and release rights around shipments can dominate access risk (see produce packing).
• Consumer products & cosmetics: changeover and packaging controls, artwork/label revision access, and exception rights are often the “sharp edge” (see consumer products and cosmetics manufacturing).

Across all industries: service accounts and privileged roles remain the consistent high-risk categories that deserve tight cadence and strong evidence.

19) Extended FAQ

Q1. What is an MES access review?
A periodic, documented audit of MES users, roles, permissions, and integration accounts to confirm least privilege, enforce segregation of duties, and maintain defensible audit trails.

Q2. How often should we do access reviews?
Risk-based. Privileged/admin access should be reviewed monthly (or per major change), while general operator access can often be semi-annual—assuming role design is tight and provisioning is controlled.

Q3. What’s the biggest red flag in an MES access model?
A single “super user” role assigned widely (especially to supervisors or service accounts). That almost guarantees bypass and weak attribution under pressure.

Q4. Do we really need to include service accounts?
Yes. Service accounts are frequently over-privileged and can change records at scale. If you don’t review them, you’re ignoring the largest blast radius identities.

Q5. How does access review relate to data integrity?
If you can’t prove access is controlled, you can’t prove records are attributable or trustworthy. Access governance supports data integrity, audit trails, and ALCOA concepts.

Related Reading
• Access + Governance: Access Provisioning | Role-Based Access | User Access Management | Segregation of Duties in MES
• Execution Controls: Execution-Oriented MES | Execution-Level Enforcement | Step-Level Enforcement | Credential-Based Execution Control | Operator Authorization Matrix
• Evidence + Integrity: Audit Trail | Data Integrity | ALCOA | Record Retention | Document Control
• Change + Validation: Change Control | Revision Control | MOC | CSV | GAMP 5 | Annex 11 | 21 CFR Part 11
• Industry Context: Industries | Pharmaceutical | Medical Devices | Food Processing | Produce Packing | Cosmetics | Consumer Products