This is a real thread for the times, where the developed world largely lives in constant hesitancy and uncertainty of the details of our social contracts. These days I will usually go to help somebody, but ask first. This way, if I satisfy the most fiercely defended criteria of informed consent, I can hardly go wrong.
It can be more subtle than one thinks. I once encountered a girl with cerebral palsy, presumably, on the tram. She had a stiff-legged gait, practically no motor control of her arms, and multiple deformities (including micrognathia, which essentially gave her a massive overbite), but most importantly she was mute and presumably intellectually impaired. She saw that I was looking at her and indicated (with a lot of excitement), that she wished to interact further.
This is where I press the pause button.
The young lady appeared to be over eighteen. She was accompanied (supervised) by another young lady, of similar age. It was safe to presume that the latter was the former's carer and perhaps legal guardian. Therefore most properly, interaction I had with the girl with cerebral palsy must be approved by the carer, otherwise (in the unlikely event) should a complaint arise, I would have trouble defending myself.
Of course, when most people see somebody like the young lady I just described in public, they tend to walk the other direction, thus this issue is rare.
