A security decision log is a running list of significant security choices, each with the date, the reason, the alternatives you rejected and an owner. A small team needs one because people forget why a setting exists, and buyers and auditors often ask for reasoning.
Where the idea comes from
Engineering teams already keep architectural decision records, often called ADRs. The ADR community defines an architectural decision as a justified design choice that addresses a requirement, and publishes several templates. A security decision log is the same habit pointed at security choices. You can reuse any ADR template.
What belongs in it
Log decisions that someone could reasonably question later.
| Decision type | Example entry |
|---|---|
| Tooling choice | Why we picked one scanner approach for pull requests |
| Exception | Why a known weak setting stays for now |
| Policy | Why contractors get read only access by default |
| Design | Why tokens expire after a short time |
| Risk acceptance | Why we deferred an upgrade, with a review date |
Do not log every ticket. Aim for a handful of entries a quarter.
A template that fits in a few lines
- Title: a short phrase, for example "Require review for infrastructure changes".
- Date and owner: who decided, and when.
- Context: what problem or risk prompted it.
- Decision: what you chose, in one or two sentences.
- Alternatives: what you considered and why you passed.
- Consequences: what gets easier, what gets harder.
- Review date: when to look again.
Store entries as markdown files in a docs folder in your repository, one file each. They get reviewed in pull requests, versioned, and found by search. The model is described in a minimal repository based GRC setup.
How it pays off
Three situations make the log worth the effort. A new engineer wants to know why a rule exists and does not have to ask. A customer asks how you decided something and you have a dated answer. An incident review asks whether a decision was reasonable given what you knew then. The log records the context you had, which makes calm review possible.
Keep it honest
Record rejected options and downsides, not only the winner. Add review dates and actually look at them in your quarterly review. Mark old entries superseded instead of deleting them, so the history stays readable.
Common mistakes
Writing entries after the fact with invented reasoning. Making the template so long nobody fills it in. Storing it in a place only one person can find. Logging decisions but never revisiting them.
Where Safeguard fits
Safeguard offers compliance and evidence automation for teams that need to show how controls operate. It also provides SBOM and dependency scanning, reachability analysis to show which findings are actually exposed, and policies and gates for pull requests. A free scan is at gold.safeguard.sh/scan.
Quick check
Is this the same as an ADR?
It uses the same format. An ADR usually records design choices, and a security decision log records the security ones.
Who writes the entries?
The person who made or proposed the decision, with a second engineer reviewing the pull request.
Sources
Last reviewed: 19 October 2026.
