In a decision on 10 November 2016 Benhaim v St Germain  SCC 48, the Supreme Court of Canada discussed causation inferences in a matter where the doctors’ breach of duty undermined the patient’s ability to prove causation.
The court concluded that a trial judge is permitted but not required to draw an inference of causation in such circumstances. An excerpt from the headnote for the majority expands:
The principles must not be interpreted in a manner that alters the burden of proof or departs from the criteria for establishing presumptions of fact. In weighing the evidence, trial judges may consider the ability of the parties to produce evidence. Whether the inference or presumption arises on the facts must be assessed according to a legal, not a scientific, standard.