At some point in establishing the business case to support a business initiative a decision needs to be made either to proceed or to not proceed. In building the business case information will have been gathered and collective knowledge will have been applied to determine it adequacy.
Risks will have been identified and presumably the cost of mitigation coupled with both their impact and the likelihood of their occurring will have been established.
A decision can be reached by balancing the benefits of the initiative against the cost of implementation, the impact on the business if it is not and the importance of its contribution into the realisation of Business Goals and Strategy. This decision needs to be also made with an appreciation of other competing initiatives in the pipeline.