The business case captures the knowledge developed about how the business will function both with and without the action or solution:

What are the business consequences if we make a decision (take an action)?

The business case is a tool developed to verify that the solution proposal meets the needs of the business and enables all organizations affected by the proposal (customers, management, operations, finance, etc.) to be knowledgeable about the endeavor.

We suggest proceeding with the Business Case if the customer is not sure to implement the business proposal and for the moment only wants to know its business consequences.