if the consequence is too remote (in time or other circumstance) from the act, the chain of causation is broken

I seem to remember there was a quite recent case in the UK that hit the legal headlines over this issue. Initially someone was convicted of grievous bodily harm when their victim was hospitalised; this conviction was successfully changed some years later to murder due to the victim having died after spending several years in a persistent vegetative state. Presumably, despite the extraordinary lapse in time, the prosecution was able to demonstrate an unbroken causal link. (‘Fraid I don’t have the case reference, though.)