Segregation of Duties in MES

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

Updated December 2025 • segregation of duties (SoD) in MES, maker-checker controls, independent verification, dual authorization, self-approval prevention, override governance, e-signature meaning, nonrepudiation, least privilege, shift realities, break-glass controls, audit-ready denial logs • Cross-industry (GxP, Med Device, Food, Chemicals, Aerospace, Electronics, Automotive, Industrial)

Segregation of Duties in MES is the practice of using a Manufacturing Execution System to enforce independent control points in manufacturing execution—so the person who performs a critical action cannot unilaterally approve, verify, release, or “fix” that same action without appropriate independent involvement. In other words: the MES prevents self-approval in the places where self-approval creates real risk. Done correctly, segregation of duties (SoD) is not bureaucracy. It is a control mechanism that stops the most common integrity failure mode in operations: “one person can make the record look compliant even when execution wasn’t.”

SoD matters because shop-floor reality is not a pristine audit scenario. It is noisy, interrupted, understaffed at times, and run under schedule pressure. When systems allow convenient shortcuts—self-verification, generic supervisor overrides, broad admin roles, shared logins—those shortcuts become the norm, then become invisible, then become the root cause behind slow QA release, repeated deviations, and weak investigations. Strong SoD in the MES makes the correct path the default path by forcing independence where it counts and making exceptions visible, time-bound, and reviewable.

Segregation of duties in MES is inseparable from broader integrity concepts like Manufacturing Execution Integrity and control concepts like Credential-Based Execution Control. It also supports operational outcomes like In-Process Compliance Enforcement and Execution-Layer Quality Controls, because those controls only work if independence cannot be bypassed by “approving yourself.”

“If the system lets one person execute, verify, override, and release, you don’t have controls—you have paperwork with a username.”

1) What buyers mean by segregation of duties in MES

Buyers mean: “Stop letting one person create the outcome and approve the outcome.” They want independence embedded in execution, not independence written into policy and hoped for during peak pressure. Specifically, they want the MES to prevent the high-risk combination of privileges that enables record manipulation, accidental approval, or deliberate bypass. This is the core maker-checker concept applied to manufacturing: the maker executes; the checker verifies; and certain decisions require an authorized approver who is not the maker.

In practice, buyers are trying to solve one or more of these realities: QA release is slow because QA doesn’t trust floor sign-offs; deviations repeat because the same person “handles” them every time; audits focus on data integrity weaknesses like shared logins and self-approvals; and investigations take too long because accountability is unclear. Strong SoD in MES is the control that breaks those patterns: it makes routine execution more trustworthy and makes exceptions more visible and governable.

There is also a strategic, forward-looking reason: if you want review-by-exception to be credible, the system must prove that routine steps were executed and verified under proper independence rules. Without SoD enforcement, “review by exception” becomes “trust the record,” and trust collapses the moment independence is questionable. That is why segregation of duties sits naturally inside manufacturing execution integrity.

2) SoD vocabulary that prevents “talking past each other”

SoD projects derail because teams use the same words to mean different things. A clean vocabulary keeps design decisions sane and auditable.

A useful mental model: SoD is not “more signatures.” SoD is “the system prevents the same identity from owning the whole decision chain where independence is required.” That’s a design constraint, not a paperwork preference.

3) Why SoD must be enforced in the MES, not only in SOPs

Many organizations attempt SoD through SOPs: “The verifier must be different from the executor.” That is a rule, but without system enforcement it becomes a suggestion under pressure. People will not intentionally violate it most of the time. They will violate it because the line is down, staffing is short, the supervisor is busy, and the system makes it easy to “just sign it.”

MES-enforced SoD is different because it blocks invalid combinations at the moment of action. That matters for both integrity and speed. When the MES forces independence, it produces a record where routine steps are inherently more trustworthy. QA review can become faster because routine evidence is structurally harder to falsify or accidentally misapply. This is one of the reasons execution systems that enforce work (not just document work) unlock faster release behavior.

If SoD is critical to your compliance posture or customer expectations, relying on SOP-only enforcement is a strategic mistake. It guarantees either slow review (because QA must distrust everything) or hidden violations (because people will “make it work”). MES-enforced SoD is how you avoid both outcomes.

4) Non-negotiables: the SoD “block test” checklist

If you want to confirm whether SoD is real in an MES, don’t start with role matrices. Start with denial tests. A system that cannot deny these combinations is not enforcing SoD—it is documenting intentions.

5) Where SoD breaks in real plants

SoD failures are predictable, and they’re rarely dramatic in the moment. They start as convenience and become culture. The most common patterns look like this: a “temporary” shared login becomes normal; a supervisor password gets used to approve things the supervisor didn’t review; an admin role is granted “just for the week” and never removed; or verifications are done by the same person because the other operator is busy. The record still looks neat, but the evidence chain becomes thin.

There are also structural failure modes that show up even in well-intentioned plants. One is role creep: over time, people accumulate permissions to solve short-term problems, and nobody revokes them because it’s inconvenient. Another is UI-only SoD: the screen hides a button, but the same action can be performed via a different screen, or an import, or an integration. A third is exception normalization: the system “allows” exceptions so frequently that exceptions become routine and independence fades.

The solution is not “write stricter SOPs.” The solution is to treat SoD as an execution rule, enforced by the same control plane that enforces steps and states. When SoD is part of runtime enforcement, the plant’s default behavior shifts: independence becomes the normal path, and exceptions become visible events that leadership can fix at the root.

6) Architecture: where SoD rules live in an execution system

SoD rules must live in the execution rule engine, not in the UI layer. The reason is simple: if the UI is the main enforcement point, any alternate pathway can bypass it. A control-grade MES treats actions as server-side transactions and evaluates SoD before committing them. This is the same architectural philosophy behind execution enforcement generally: the system must be able to block wrong actions, not merely warn about them.

In practice, SoD enforcement depends on three pieces working together: (1) a state model that defines what “complete,” “verified,” “approved,” “blocked,” and “released” actually mean (often implemented via a real-time execution state machine), (2) action-level rules that prevent invalid transitions (implemented via step-level execution enforcement and operator action validation), and (3) identity/context binding so approvals apply to the correct object and cannot be “misplaced” (implemented with execution context locking).

SoD architecture should also treat denial as evidence. When an action is denied due to SoD, the denial should be logged with context and reason. Those denial logs become proof that controls are active, and they also become a management signal: if a particular step generates frequent SoD denials, that’s a staffing or workflow design issue worth fixing.

7) Step-level SoD patterns: execute vs verify vs approve

SoD becomes concrete at the step level. The key is to define which steps require independence and what independence means. Many steps do not need independent verification; forcing it everywhere creates friction and drives bypass behavior. High-risk steps, however, absolutely need it. A mature approach is risk-based: identify the steps where a single mistake would create meaningful risk (patient safety, consumer safety, mislabel, mix-up, major compliance failure, or significant financial exposure) and enforce independent verification there.

For the highest-risk cases, independence is often implemented as “concurrent” or “dual” controls. That’s where concurrent operator controls patterns matter: the system requires two distinct identities to confirm a critical result or action, and it makes it difficult to fake independence by simply swapping credentials.

8) SoD in quality workflows: deviations, holds, dispositions, release

Segregation of duties is just as important in quality workflows as it is in production steps. In many organizations, the biggest integrity risk is not a shop-floor step; it is the ability to “resolve” exceptions without independent scrutiny. If one person can initiate a deviation, write the investigation narrative, approve the disposition, and release the batch/order, the system is enabling a single-person truth-making machine. That might be convenient, but it is not defensible.

SoD in quality workflows usually includes at least three separations: (1) the person who performs the action is not the same person who verifies it, (2) the person who detects/logs the exception is not the same person who approves the disposition, and (3) the person who benefits from schedule outcomes is not the sole approver of release-impacting decisions. These separations don’t have to create bureaucracy if the system routes exceptions efficiently and makes routine paths fast.

This is where terms like Execution-Time Deviation Detection and Automated Execution Hold Logic connect. If the system detects a deviation condition during execution, it can force the process into an exception state and require independent disposition. If it triggers a hold, it can enforce that hold removal requires independent authority. That’s how you prevent “keep going and explain later” from becoming the normal operating mode.

SoD must also respect status semantics like hold/quarantine. If a held state can be removed by the same person who caused or logged the exception, the hold is not a control; it is a suggestion. When holds are real controls, they become credible levers that support fast but safe operations.

9) Authentication strength and e-signature meaning

SoD is not just “different usernames.” It is independent decisions made by independently accountable people. That requires strong identity controls and, for high-risk actions, stronger authentication at the moment of approval. If a supervisor’s password is written on a clipboard, SoD collapses even if the system “technically” requires a different role.

A mature MES approach uses step-up authentication for high-risk approvals (hold release, deviation disposition, critical override, release) so that approvals cannot be casually replayed. It also captures signature meaning: what was approved, what evidence was visible, what exceptions were open, what state the batch/order was in, and why the approval was allowed. This is where SoD intersects tightly with Credential-Based Execution Control: credentials are not only for access; they are for control and nonrepudiation.

One subtle but important point: the MES should block “approval by proximity.” Approvers must see what they are approving in context. The system should not make it easy for someone to approve a step from a vague prompt (“please approve this”) without seeing the underlying evidence and exception summary. The fastest path should be the most defensible path, not the least informed path.

10) Shift realities: small teams, night shift, and pragmatic controls

SoD design has to be honest about staffing reality. Some lines run with two people. Some facilities have limited QA coverage on nights. Some operations are remote, distributed, or have shared specialists across sites. If SoD is designed as “perfect independence everywhere,” the plant will demand bypasses. That outcome is predictable and avoidable.

The right approach is risk-based SoD with pragmatic exception paths. For the highest-risk steps, independence should remain non-negotiable. That may mean scheduling verification resources appropriately or using remote verification by an independent, credentialed verifier. For medium-risk steps, independence can be enforced through time separation (for example, verification must be performed later by a different role before close/release) or through targeted sampling where appropriate. For low-risk steps, independence may not be required at all.

What should never happen is silent bypass. If staffing makes a required SoD control impossible, the system should force a governed exception: a break-glass authorization, a time-bound delegation, or a documented temporary authority decision. Those events should be visible and trendable so leadership can fix the structural problem rather than normalize the workaround.

11) Override governance: break-glass, temporary authority, dual approval

Overrides are where SoD either proves itself or collapses. If the system allows a supervisor override that effectively says “do whatever you want,” independence disappears. If overrides are too hard, operations will force IT or admins to create backdoors. The practical solution is governed override design.

A strong override model typically includes: explicit override classes (what is being bypassed), explicit approval boundaries (who can approve which override class), explicit reason capture, and explicit review requirements. For critical overrides, it includes dual approval or independent review. For emergencies, it includes break-glass: a time-bound, narrowly scoped authority that is automatically flagged for post-event review. If break-glass becomes routine, that is an operational failure signal, and the system should make it obvious.

SoD must apply to overrides themselves. The person requesting the override should not be the only person who can approve it. That separation is the whole point: the system prevents one identity from owning the entire exception chain.

12) Integrations and bypass risk: APIs, imports, service accounts

Many SoD programs fail because the plant enforces SoD in the UI but integrations bypass it. If an API can “complete” a step, post an adjustment, or close an order without the same SoD checks, the SoD model is not authoritative. It becomes a user-experience constraint rather than a control.

SoD must be enforced server-side on every action regardless of source. That includes handhelds, terminals, tablets, APIs, imports, PLC interfaces, and integration connectors. Service accounts must be narrowly scoped and should never be superusers. If a service account can do everything, it becomes the easiest bypass path. If a service account can approve things, you’ve effectively eliminated SoD because the “approver” is no longer a person.

There is also an integration sequencing reality: sometimes ERP needs consumption transactions, WMS needs status states, or LIMS needs sample events. The correct approach is for external systems to consume validated state from the MES (or from a shared authoritative rule layer) rather than create state that overrides MES controls. If two systems can independently decide that an item is released, SoD and status enforcement are both compromised.

13) Audit-ready evidence: what the record must prove

SoD is only as defensible as the evidence it produces. A credible record must show: who executed the step, who verified it, that those identities were distinct, that both were eligible/authorized/qualified at the time of action, what evidence was reviewed at verification, and what the MES denied. Denied-action logs matter because they prove the control was active—not merely configured in a policy document.

SoD evidence should also be usable operationally. During investigations, the question is not merely “who signed.” The question is “who made the decision, what did it mean, and was it independent?” A system that captures meaningful attestations and independence constraints reduces investigation time-to-truth because it reduces ambiguity and makes accountability clear.

Finally, SoD evidence supports faster QA review when implemented as part of a broader execution integrity stack. If routine steps show clean independence with no overrides, QA can focus on exceptions. If the system allows self-verification, QA has to treat every verification as suspicious. That is the operational cost of weak SoD: slower release forever.

14) Metrics that matter: integrity signals without control fatigue

The goal is not to maximize denials; it is to maximize integrity while minimizing friction. A strong SoD program tracks metrics that reveal both control health and workflow health.

A simple rule: if your SoD metrics always look “perfect,” you may have a blind spot. Either the system is not enforcing, or people have found bypass paths, or your logging is incomplete. Real controls generate some friction signals. The question is whether those signals are used to improve the system and staffing model rather than ignored.

15) Validation & ongoing assurance: keeping SoD real over time

SoD should be validated as behavior, not as configuration. Validation must prove that prohibited combinations are blocked under realistic scenarios, that allowed combinations are allowed cleanly, and that denials and approvals produce audit-ready trails with meaning. This is best done with scenario-based testing: execute/verify, initiate/approve deviation, place/remove hold, request/approve override, and attempt bypass via API/import.

Ongoing assurance matters because SoD degrades over time. Roles change, people move, contractors arrive, and “temporary” access becomes permanent. A mature program includes periodic access reviews, role cleanup, and explicit monitoring for role creep. It also includes monitoring for shadow controls: shared credentials, password-sharing, and workarounds that push approvals off-system. If approvals happen off-system, the MES cannot protect you, and SoD becomes a narrative rather than a control.

The forward-looking approach is to treat SoD as part of operational excellence, not just compliance. Strong SoD reduces rework and investigation load because it prevents a class of integrity failures from ever being recorded as valid work.

16) Copy/paste demo script and selection scorecard

If you want to evaluate SoD in an MES vendor demo (or in an internal system review), force the “bad day” scenarios. Do not accept “we support SoD.” Prove denial behavior and bypass resistance.

17) Selection pitfalls: how SoD gets faked

• UI-only enforcement. If another interface can perform the action, SoD is bypassable.
• Shared credentials. “Different usernames” is meaningless if logins are shared or swapped.
• Supervisor password culture. If supervisors approve without reviewing, independence is theater.
• Permanent admin on the floor. This is a control-killer disguised as productivity.
• SoD everywhere. Over-enforcement creates friction, then bypasses; SoD must be risk-based.
• Break-glass without review. If emergency authority has no mandatory follow-up, it becomes routine.
• Service accounts as approvers. Non-human approval undermines independence by design.
• No denial logs. If you can’t show blocked attempts, you can’t prove controls operated.

18) How this maps to V5 by SG Systems Global

V5 supports segregation of duties as an execution control pattern rather than a policy-only pattern. At the execution layer, V5 MES supports action-level authorization and independent verification patterns, including rule-driven denials when the same identity attempts to execute and verify or to own an end-to-end exception chain. The enforcement model aligns with role-based execution authority and operator action validation, and it can be strengthened by execution context locking so approvals and verifications are bound to the correct order/step context. For exception governance and release-impacting decisions, V5 QMS supports deviations, dispositions, approvals, CAPA, and release blocks so independent authorization is enforceable where it matters. For platform context, see V5 solution overview and V5 Connect API for integration patterns that avoid bypass.

19) Extended FAQ

Q1. What is segregation of duties in MES?
It is the MES enforcing independence rules so one person cannot unilaterally execute and approve/verify/release the same critical work or exception chain, with denials and approvals captured as audit-ready evidence.

Q2. Is SoD only for regulated industries?
No. Regulated industries feel it first, but any industry that cares about traceability, safety, fraud prevention, and stable execution benefits from maker-checker controls on critical actions.

Q3. What is the fastest test to see if SoD is real?
Try to self-verify a critical step and try to self-approve a deviation/hold/disposition. If the system blocks across UI and API/import, and logs denials, SoD is real.

Q4. Won’t SoD slow production?
It can if you enforce independence everywhere. Done correctly, it is risk-based: high-risk steps require independence, low-risk steps don’t, and exceptions are governed rather than bypassed. Over time, it reduces rework and QA forensic review, which improves cycle time.

Q5. What’s the biggest SoD anti-pattern?
Permanent “admin” or shared supervisor overrides on the shop floor. It creates a backdoor that turns independence into theater.

Q6. How do you handle small shifts with limited staffing?
Use pragmatic, governed options: remote independent verification, time-separated verification before close/release, or break-glass with mandatory review. Never make silent bypass the routine path.

Related Reading
• Glossary Crosslinks: Credential-Based Execution Control | Manufacturing Execution Integrity | In-Process Compliance Enforcement | Execution-Layer Quality Controls | Automated Execution Hold Logic | Execution-Time Deviation Detection
• Implementation Guides: Role-Based Execution Authority | Operator Action Validation | Concurrent Operator Controls | Execution Context Locking | Step-Level Execution Enforcement | Real-Time Execution State Machine | Review by Exception