What is the mitigation burden of an employer in a wrongful dismissal action?

It is well-established that a dismissed employee must mitigate or minimize any damages arising out of the wrongful dismissal by making reasonable efforts to secure alternate, comparable employment: Red Deer College v. Michaels, 1975 CanLII 15 (SCC), [1976] 2 S.C.R. 324, at p. 331. However, it is equally clear that the employer bears the burden of proving the employee’s failure to mitigate; and that this burden is not light: Michaels, at p. 332. The mitigation inquiry is fact-driven and considers all the relevant circumstances. The question is whether the employee has made reasonable efforts in the circumstances to find comparable employment: Michaels, at pp. 331-32.