I have always understood that in HR we're not here to 'police' adherence to policy and what managers can and can't do. Instead we are there to advise on best practice, organisational policy and employment law - and it is for senior managers to then make final decision on the actions that are needed.
Sometimes HR can get the blame for things going wrong in an organisation, when staff member's ask 'why didn't HR do something'? When in fact, the HR team may have strongly advised against something happening but does not have final authority and the manager does it anyway.
What are your views? In what contexts should HR be the organisational 'police' (if at all), and when should we be advising and then leaving it to the manager to make their final decision?