What is the impact of retained and instructed physicians having on the medical evidence of a plaintiff?

In Meghji v. Lee, 2011 BCSC 1108 at para. 214, varied on other grounds 2014 BCCA 105, Mr. Justice Johnston provided the following useful observation about evaluating medical evidence given by such non-treating physicians: Where causation of injuries is in issue, and the bulk of the medical proof of a plaintiff’s injuries is derived from experts retained and instructed by counsel, a trier of fact must spend more time evaluating the evidence in order to determine how much weight should be given to it. A physician who thoroughly examines a patient soon after an accident, and who regularly follows that patient with further examinations is in a better position to opine on causation than is a physician who examines months or even years after an accident. Evaluation of the expert opinion evidence is made more difficult in this case because each expert has been provided with masses of documentary material generated by the other experts, most of whom have been retained and instructed by counsel. A trier of fact must at least consider whether providing this much material is intended to influence each new expert’s opinion, and evaluate each expert’s opinion in order to determine whether the opinion is the product of the expert’s independent examination and thought, or has been swayed by the opinions of others or their sheer volume, and, if so, to what extent.