"Here are some warning signs that a constraint is distorting the design of its host object." #readingToday

Here are some warning signs that a constraint is distorting the design of its host object. 1. Evaluating a constraint requires data that does not otherwise fit the object's definition. 2. Related rules appear in multiple objects, forcing duplication or inheritance between objects that are not otherwise a family. 3. A lot of design and requirements conversation revolves around the constraints, but in the implementation, they are hidden away in procedural code.

Domain-Driven Design, Eric Evans