Argentina, its anecdotal (and also not what you're specifically looking for) but we approached our neighbours in our case and they were very amenable to us cutting back the trees on our side.
In fact, the following year they did a fair bit of cutting back on their side.
Has made the world of difference to our garden. (obviously not all neighbours will be the same)
I heard the same view as wbbs above, but am not sure how hard and fast that is. In fact we had a chat with the neighbours first, with the backup of finding the legal view later if needed.