Why have roles and responsibilities?

There is a very strong case that everyone should have their roles and responsibilities defined, typically in the form of terms of reference. People need to know what they are supposed to be doing, whom they should report to and who reports to them in order to do their job. The importance of this varies from job to job, and the requirement for definition needs to be tempered with the need for flexibility. However, for safety and mission-critical roles it is a high-risk strategy not to have such terms of reference.