Is there any case law where a client of a large law firm is required to change counsel?

The question of the consideration to be given to the competing value that a litigant should not be deprived of the counsel of his or her choice has been commented on by Cory J. in his reasons in MacDonald Estate v. Martin, supra at page 1270: The other factor to be weighed against maintaining the integrity of the justice system was that litigants ought not to be lightly deprived of their chosen counsel. It seems to me that to give undue weight to this factor would unduly benefit the large corporate clients who are said by my colleague to be the raison d’être of the larger firms. It is they who would retain counsel of their choice and primarily benefit from a change in the irrebuttable presumption of shared knowledge. I can see no reason for extending any special benefit or privilege to such clients of large firms. They, like any client who must seek new counsel, will suffer from inconvenience, loss of time and the inevitable worry and concern over such a change. However, the legal profession has many able counsel. The requirement of change imposed on a client is, on balance, a small price to pay for maintaining the integrity of our system of justice.