There's a funny - and poorly defined - thing that often gets mentioned in the UK these days, the 'duty of care'.
This seems to be interpreted as if you are aware of something dangerous/untoward which you can do something about but don't, then you are not fulfilling your general duty of care. There was something about this which came out of the CAA a year or two back but it didn't really give any definitive rules.
Don't know where the concept comes from but it seems to crop up in all walks of life these days!