The change advisory board is an important concept in change management. It is a group of key stakeholders of changes and they serve to advise and assist the change manager in assessing and prioritizing changes. It is an advisory body that does not have responsibility for final approval of changes. That responsibility lies with the change authority, who consults with the CAB and IT management.
The change authority is actually a role that in a best practice world is assigned to a single accountable individual. But in some cultures groups or committees are given accountability. If this is the case in your environment then the CAB can be assigned the role of change authority but it should not be considered best practice.
Note: testing may confuse the terms change manager and change authority. Specifically, the change authority has responsibility for approving individual changes, while the change manager has responsibility for the change process. However change manager may be the correct answer for a question such as “who has responsibility for approving changes”, if change authority is not one of the options.
The CAB is made up of experts and stakeholders for any given change. Although there is a core group of CAB members, its extended membership changes to match the needs of each given change. This means that every change could in theory have a unique CAB configuration. Every change that potentially impacts customers and end-users should include customer and end-user representation in the CAB.
Physical CAB meetings tend to have more liabilities than advantages. ITIL suggests that CAB meetings should be virtual and facilitated by technology. This increases the pace and quality of change management, while ensuring that each change has the appropriate membership on its CAB.
Given the importance placed on the urgent change process in ITIL, it is natural that it would have a means of providing urgent assessment and prioritization of changes. There is an Emergency CAB that is a sub-set of core CAB. This group can convene very quickly to advise and assist the change authority (change manager) on urgent changes. This committee ensures that change authorities have the benefit of sound advice before approving urgent changes.