In a motor vehicle accident where there may be multiple causes of damage or injury, can a defendant escape full liability?

Athey v. Leonati gave guidance in cases where there may be multiple causes of damage or injury. Once causation is found, there is no basis for a reduction of liability just because of the existence of other preconditions, the defendants remain liable for all injuries caused or contributed to by their negligence. Apportionment between multiple tortuous causes is allowed by provincial negligence statues, each defendant remains fully liable to the plaintiff for the injury, since each was a cause, but they can seek contribution and indemnity one from the other. However, where there is a suggested apportionment between tortuous and non‑tortuous causes, that is contrary to the principles of tort law, as the defendant would escape full liability even though he or she caused or contributed to the entire injury.