Part 2 of 3: Choosing the Right Documentation Method
Use cases often get dismissed in agile environments as heavyweight documentation that slows down development. But this misses their fundamental value: use cases excel at capturing complex business logic, handling intricate workflows, and ensuring comprehensive coverage of system behavior. When applied correctly, they can prevent costly misunderstandings and reduce development rework. The key is knowing when their detailed approach provides more value than overhead.
When Use Cases Are the Right Choice
Use cases shine in specific contexts where their comprehensive approach addresses real project needs rather than creating unnecessary bureaucracy.
Complex Business Process Automation
When you’re automating existing business processes that involve multiple decision points, exception handling, and regulatory compliance, use cases provide the systematic coverage needed to handle all scenarios correctly.
Consider an insurance claims processing system. The main workflow might seem straightforward, but the extensions cover dozens of scenarios: missing documentation, disputed claims, fraud detection, regulatory reporting, and integration with external systems. A user story approach would likely miss critical edge cases that cause problems in production.
Systems with High Error Costs
When mistakes in requirements lead to significant financial, legal, or safety consequences, the comprehensive approach of use cases justifies their overhead. Medical device software, financial trading systems, and safety-critical applications benefit from systematic requirements coverage.
The detailed exception handling in use cases helps developers understand not just what should happen when things go right, but what should happen when things go wrong—which is often more critical in high-stakes systems.
Large, Distributed Teams
When requirements need to be understood by many people across different teams, time zones, and organizations, use cases provide self-contained documentation that reduces dependency on ongoing conversation.
A development team in one country can implement features based on use cases written by business analysts in another country without constant clarification meetings. This doesn’t work as well with user stories, which assume close collaboration and frequent communication.
Writing Use Cases That Actually Help
The difference between useful use cases and bureaucratic overhead lies in how they’re written and applied.
Focus on User Goals, Not System Functions
Good use cases describe what users are trying to accomplish, not what the system does internally. The goal is “complete customer order” not “update database records and send confirmation email.”
This user-centric approach keeps use cases focused on value delivery rather than implementation details, making them more useful for both stakeholders and developers.
The Right Level of Detail
Use cases should be detailed enough to guide implementation but not so detailed that they constrain design unnecessarily. Specify what information users need and what decisions the system should make, but avoid specifying user interface layout or technical implementation approaches.
// Too vague
"User searches for products"
// Too detailed
"User clicks the search button in the top-right corner of the navbar, which triggers a GET request to /api/search with query parameters"
// Just right
"User enters search terms and receives ranked results showing product name, price, and availability within their preferred delivery area"Extension Scenarios That Matter
Don’t try to cover every possible exception—focus on extensions that either happen frequently or have serious consequences when handled poorly. A 1% edge case that breaks the user experience matters more than a dozen theoretical exceptions that never occur in practice.
Use data from existing systems, customer support tickets, and user research to identify which exceptions actually need detailed specification.
Use Cases for Stakeholder Communication
One of the strongest advantages of use cases is their effectiveness as stakeholder communication tools. They provide a format that both technical and non-technical stakeholders can understand and validate.
Walking Through Scenarios
Use cases enable stakeholders to “walk through” system behavior step by step, identifying gaps, conflicts, and missing requirements before development begins. This collaborative review process often uncovers assumptions and misunderstandings that would otherwise become expensive change requests.
The detailed format makes it easier for stakeholders to spot problems: “Wait, what happens if the customer wants to return only some items from their order?” becomes an obvious question when reading a comprehensive use case.
Cross-Functional Understanding
Use cases help different stakeholders understand how their requirements interact. The marketing team sees how their promotional pricing requirements affect the checkout process. The customer service team understands how order modifications impact inventory management.
This cross-functional perspective is harder to achieve with user stories, which tend to focus on individual features rather than end-to-end processes.
Use Cases in Agile Environments
The perception that use cases don’t work in agile environments is often based on misapplication rather than fundamental incompatibility. Use cases can support iterative development when applied thoughtfully.
Evolutionary Use Cases
Start with high-level use cases that capture the essential workflow, then add detail iteratively as understanding improves. Early use cases might focus on the main success scenario, with extensions added based on user feedback and testing.
This approach provides the systematic thinking benefits of use cases while maintaining the flexibility that agile development requires.
Use Cases as Planning Tools
Use cases can inform sprint planning and story writing rather than replacing them entirely. A detailed use case can be broken down into multiple user stories that each deliver part of the overall workflow.
This ensures that individual stories contribute to coherent end-to-end functionality rather than becoming isolated features that don’t work well together.
Tools and Techniques for Effective Use Cases
The right tools and techniques can make use case development more efficient and valuable.
Use Case Modeling
Visual use case diagrams help stakeholders understand the scope of system functionality and the relationships between different actors and goals. They’re particularly valuable for identifying missing use cases and overlapping functionality.
But don’t let diagram creation become more important than understanding user needs. Use diagrams to support communication, not to satisfy methodology requirements.
Collaborative Use Case Development
The most effective use cases are developed collaboratively rather than written in isolation. Facilitate workshops where stakeholders walk through scenarios together, identifying steps, decision points, and exception conditions collectively.
This collaborative approach ensures that use cases reflect actual user workflows rather than assumptions about how processes should work.
Measuring Use Case Effectiveness
Good use cases should measurably improve project outcomes. If your use cases aren’t making development more predictable, stakeholder communication clearer, or system quality better, they might not be the right tool for your context.
Coverage Metrics
Track whether your implemented system handles the scenarios described in your use cases. Are there gaps between what was specified and what was built? Do users encounter scenarios that weren’t covered in the original use cases?
This feedback helps you calibrate the right level of detail for future use case development.
The Integration Challenge
Individual use cases might be well-written, but the real test is how well they work together to describe a coherent system. Use case integration is where many requirements efforts break down.
Build processes for reviewing use cases as a complete set, identifying overlaps, gaps, and conflicts between different scenarios. The goal is a collection of use cases that provides comprehensive coverage without redundancy or contradiction.
Understanding when and how to use use cases effectively sets the foundation for our next discussion: when user stories provide a better approach and how to write stories that actually drive successful development.
This is Part 2 of a 3-part series on use cases vs user stories. Next: “When to Choose User Stories: Agile Documentation That Drives Development”
