Peer review, often called code review in software teams, is an independent check of a proposed change by someone other than the author before the change is accepted. In compliance and change management contexts, peer review is a control that helps catch errors, insecure patterns, and unauthorized changes before they reach production.
In a SOC 2 examination, auditors frequently test whether in-scope changes received the required review or approval. For engineering teams, that usually means a reviewed pull request, merge request, or equivalent workflow with a clear reviewer distinct from the author.
In simple terms, peer review answers:
- Did someone other than the author inspect the change before it shipped?
- Was the review required by policy and enforced by tooling?
- Can you prove reviews happened for changes during the audit period?
Why Peer Review Matters
Peer review matters because:
- It supports segregation of duties between who writes a change and who accepts it
- It reduces the chance that a single person can push unreviewed code to production
- It creates durable audit evidence when reviews are recorded in systems like GitHub or GitLab
- It connects day-to-day engineering practice to change management controls auditors already expect
- It gives control owners a concrete operating signal when reviews are skipped
Peer review is not only a culture preference. When your control description says changes require review before production deploy, auditors will sample changes and look for that review.
Peer Review, Code Review, and Pull Request Approval
These terms overlap in practice:
| Term | Typical meaning in SOC 2 evidence |
|---|---|
| Peer review | Independent review of a change by a qualified peer |
| Code review | Peer review focused on source code, tests, and related artifacts |
| Pull request approval | A recorded approve action on a pull request or merge request |
| Branch protection | Repository rules that block merges without required reviews or checks |
A strong control usually combines policy, tooling, and evidence. Policy says review is required. Branch protection or equivalent rules enforce it. Pull request approvals and review comments show it happened.
What Good Peer Review Looks Like for Audits
Auditors commonly look for:
- A named reviewer different from the author
- An approval or explicit review completion before merge or deploy
- Timestamps that place the review before production release
- Scope coverage: production or in-scope repositories actually enforce the rule
- Exceptions handled through an approved emergency path, not silent bypasses
Review quality still matters to engineering outcomes, but audit testing usually focuses on whether the required independent review occurred and was recorded. Ask your auditor what attributes they will check on each sample.
Example Evidence Matrix
| Activity | Example evidence |
|---|---|
| Normal feature change | Pull request with required approval, linked ticket, merge commit, deploy record |
| Infrastructure change | Reviewed IaC pull request plus apply logs |
| Hotfix | Emergency change ticket, post-implementation review, and follow-up PR review if policy requires it |
| Policy enforcement | Branch protection export or org rule settings with date |
| Bypass attempt | Blocked merge log, or documented exception if a bypass was approved |
For broader change evidence packages, see Change Management Evidence for SOC 2.
How Auditors Typically Test Peer Review
In SOC 2 Type 2 testing, auditors often:
- Obtain a population of production changes for the period
- Select an audit sample
- Trace each sampled change to a ticket and a review or approval record
- Confirm the reviewer was not the author
- Note a control deviation when review is missing, late, or self-approved
SOC 2 Type 1 work may focus more on whether review requirements are designed and enforced at a point in time. Type 2 asks whether the control operated across the period.
Related testing concepts: Test of Design vs Test of Operating Effectiveness and What Is an Audit Population?.
Peer Review and Segregation of Duties
Peer review is one practical way to separate duties in software delivery. It does not replace every other access control. Production credentials, deploy permissions, and admin roles still need least-privilege design.
Common weak spots:
- Authors who can approve their own pull requests
- Admins who can bypass branch protection without logging
- Shared bot accounts that blur who actually reviewed
- Repositories that are in scope but never had protection enabled
- Review requirements that apply only to some teams while other production repos remain unprotected
If self-approval is possible, expect questions. If bypasses exist, retain who used them, why, and how the change was reviewed afterward. Documented emergency paths are easier to defend than silent force-pushes.
Operating Tips for Engineering and Compliance Teams
- Write the control in plain language that matches how your repos actually work
- Turn on required reviews for every in-scope production branch
- Forbid author self-approval where your control requires independence
- Link tickets to pull requests so sampling is traceable
- Keep branch protection exports or screenshots with dates for design evidence
- Define what happens for hotfixes, then follow that path every time
- When a miss happens, track remediation instead of rewriting history
Common Mistakes
- Describing mandatory peer review in policy while leaving branch protection optional
- Allowing author self-approvals on in-scope repositories
- Reviewing after deploy and treating that as the same as pre-merge review
- Keeping no link between the change ticket and the pull request
- Excluding emergency changes from any after-the-fact review trail
- Assuming a CI check alone is peer review (automated checks help, but they are not an independent human peer unless your control says otherwise and your auditor agrees)
- Rebuilding the change population after removing unreviewed deploys
How AuditFlo.co Helps
AuditFlo.co helps teams retain continuous evidence collection and audit-period history for operational artifacts when those records are stored or linked through connected systems and workflows your team already uses, such as GitHub and Jira.
That history can make it easier to show reviewed changes across the period. AuditFlo.co does not perform code reviews, does not approve pull requests, does not issue SOC 2 reports, does not certify compliance, and does not replace auditors.
To see the workflow for your stack, request a demo.
Key Takeaway
Peer review (code review) is an independent check of a change before acceptance. For SOC 2 change management evidence, enforce it with branch protection, record pull request approvals by someone other than the author, and keep those records available for period sampling.