Enterprise Architecture Decision Records
Every enterprise technology estate is shaped by thousands of decisions made over years: database selections, framework choices, integration patterns, deployment strategies, and vendor selections. Yet in most organisations, these decisions are poorly documented, their rationale is lost when the people who made them move on, and teams repeatedly revisit settled questions because no one can find or recall why a decision was made.
Architecture Decision Records (ADRs) address this problem with elegant simplicity. An ADR is a short document that captures a single architecture decision, its context, the options considered, the decision made, and the consequences of that decision. The format is lightweight enough to be completed in thirty minutes yet structured enough to provide lasting value.
Michael Nygard’s original ADR proposal remains the definitive reference, and its simplicity is its greatest strength. But scaling ADRs from a single team practice to an enterprise governance tool requires intentional design.
The ADR Structure
A well-constructed ADR contains five essential elements:
Title: A short, descriptive name that makes the decision identifiable. “Use PostgreSQL for the customer data service” is clear and specific. “Database decision” is not.
Context: The circumstances that necessitated the decision. What problem is being solved? What constraints exist? What has changed since the last relevant decision? The context section should provide enough information for a reader unfamiliar with the project to understand why a decision was needed.
Decision: The choice that was made, stated clearly and concisely. “We will use PostgreSQL 13 as the primary data store for the customer data service, deployed as Amazon RDS instances.”
Consequences: The expected outcomes of the decision, both positive and negative. Good ADRs are honest about trade-offs: “PostgreSQL provides strong consistency and ACID compliance, which our regulatory requirements demand. However, this choice limits our ability to leverage document-oriented query patterns and may require schema migrations for future data model changes.”
Status: The current state of the decision — proposed, accepted, deprecated, or superseded. When a decision is superseded, the ADR should reference the new decision that replaces it, creating a traceable history.
Some organisations extend this structure with additional sections: options considered (with brief evaluation of each), stakeholders consulted, and review date. These additions increase the documentation burden but provide additional value for consequential decisions.
Scaling ADRs Across the Enterprise
Individual teams adopting ADRs is straightforward. Scaling the practice across an enterprise with dozens or hundreds of teams requires addressing discoverability, governance integration, and cultural adoption.
Storage and Discoverability: ADRs must be findable to be useful. Two storage patterns have emerged:
Colocated with code: ADRs are stored in the repository they apply to, typically in a docs/adr or docs/decisions directory. This ensures that the decisions travel with the code and are accessible to anyone working on that codebase. Tools like adr-tools (a command-line tool for managing ADRs) support this pattern.
Centralised catalogue: Enterprise-wide ADRs are stored in a central repository or wiki, searchable by topic, technology, team, and date. This enables cross-team discovery: a team considering a database choice can search for ADRs from other teams who have made similar decisions.
The optimal approach for enterprises is both: team-level ADRs colocated with code, and enterprise-level ADRs (those affecting multiple teams or establishing organisation-wide patterns) in a centralised catalogue. A lightweight indexing process that connects team-level ADRs to the central catalogue enables enterprise-wide search.
Governance Integration: ADRs can complement or replace traditional architecture review board processes. Rather than requiring teams to present proposals to a review board and receive verbal approval, the ADR process requires teams to document their decision in a structured format and submit it for asynchronous review.
For decisions that affect only a single team and use established patterns, the ADR serves as documentation with lightweight peer review. For decisions with broader implications — adopting a new technology, changing an integration pattern, or deviating from established standards — the ADR triggers a more thorough review process.
This graduated approach preserves governance rigour for consequential decisions while eliminating bottlenecks for routine ones. The ADR itself becomes the governance artifact: a permanent record of what was decided, why, and by whom.
Cross-Referencing and Linking: As the ADR corpus grows, relationships between decisions become important. A decision to adopt microservices architecture influences subsequent decisions about service communication, data management, and deployment. Cross-referencing related ADRs creates a decision network that provides context for new decisions.
Cultural Adoption Challenges
The technical aspects of ADR implementation are straightforward. The cultural aspects are more challenging.
Resistance to documentation: Engineers who perceive ADRs as bureaucratic overhead will produce low-quality records or avoid creating them. The key to overcoming this resistance is demonstrating value quickly: when a new team member can understand a complex architectural choice by reading a two-page ADR instead of spending days asking questions, the value is self-evident.
Decision avoidance: Some teams use the ADR process to avoid making decisions — cycling through options, requesting more analysis, and delaying commitment. The ADR process should have a time-bound decision cycle with a clear escalation path for decisions that cannot be resolved at the team level.
Retrospective honesty: ADRs are most valuable when they honestly assess trade-offs and acknowledge uncertainty. A culture that punishes decisions that later prove suboptimal will produce ADRs that overstate confidence and understate risk. The organisation must distinguish between decisions that were well-reasoned but proved wrong (acceptable) and decisions that were careless or uninformed (not acceptable). The ADR provides the evidence for this distinction.
Maintaining currency: ADRs lose value when they describe decisions that have been superseded without updating the record. A process for regularly reviewing ADRs and marking deprecated decisions prevents the catalogue from becoming misleading. Some organisations tie ADR reviews to quarterly architecture reviews or to major technology changes.
ADRs as Organisational Memory
The compound value of ADRs emerges over time. After a year of consistent practice, an organisation has a searchable corpus of technology decisions that captures institutional knowledge, prevents repeated debates, and provides a decision-making trail for auditors and new team members.
Onboarding acceleration: New team members can read the ADR log to understand the major decisions that shaped the system they are joining. This is dramatically more efficient than relying on verbal knowledge transfer, which is incomplete, inconsistent, and unavailable when the original decision-makers have moved on.
Decision quality improvement: When teams know their decisions will be documented and reviewed, they tend to be more thorough in their analysis and more honest about trade-offs. The documentation discipline itself improves the decision-making process.
Pattern identification: A corpus of ADRs reveals patterns in technology decisions across the organisation. Multiple teams independently choosing the same messaging platform suggests an emerging standard. Multiple teams struggling with the same architectural challenge suggests a need for a shared solution or pattern.
Audit and compliance: In regulated industries, ADRs provide evidence that technology decisions were made deliberately, with appropriate consideration of alternatives and consequences. This documentation is valuable during audits, due diligence processes, and regulatory reviews.
Architecture Decision Records are one of the highest-value, lowest-cost practices available to enterprise technology organisations. They require no tooling beyond a text editor and a version control system. They impose minimal overhead — a good ADR takes thirty minutes to write. And they produce lasting value that compounds over time as the organisational knowledge base grows. For CTOs seeking to improve decision-making quality and institutional memory, ADRs are a practice that delivers disproportionate returns.