Duty of care
May I ask all practitioners of LARS - Regardless of the new rules, if you have identified an aircraft which is in receipt of a FIS, and you see that it is going to get extremely close to another aircraft, would you tell it or not?
I know I would, the only reason I wouldn't is if I had a higher service aircraft that needed my attention due to a safety related issue.
Duty of care is badly worded in these things - any ATCO worth his or her salt would warn an aircraft if there was perceived risk, whatever the service. However if you have not identified the FIS traffic, or if you are too busy with higher priority traffic, say RAS, then you can only do so much.
Duty of Care should take everything into consideration