What is the test for determining whether a plaintiff is a contributory or a cause?

In Doobay v. Fu, 2020 ONSC 1774, Justice Bale granted the plaintiff’s request to include “caused or contributed” in the wording of the causation question. Justice Bale’s determination was based on his assessment of the most clear way to express the causation question to the jury in a case involving physician, hospital and nurse defendants, against whom damages were sought not only for their individual breaches but also due to their failure to work as a team: Doobay, at para. 24. In a case involving multiple defendants, Justice Bale determined that the clearest expression of the “but for” test was to use the words “caused or contributed”.