Complex business rules in Laravel often end up duplicated across Eloquent queries and in-memory PHP checks, violating the Single Responsibility Principle. The Specification Pattern solves this by encapsulating each business rule into a dedicated class with two methods: `isSatisfiedBy()` for in-memory validation and `apply()` for Eloquent query building. A concrete VIP customer example demonstrates how to define a `Specification` interface, implement `IsVipCustomer`, and compose rules using `AndSpecification`. This approach provides a single source of truth for business logic, bridges the gap between database filtering and in-memory validation, and makes unit testing trivial. The pattern is recommended for dynamic, frequently-changing rules that must work in both contexts, not for simple one-off queries.
