The taxpayer had succeeded in an appeal from a prior taxation year, in which the taxpayer's motor vehicle expenses were deductible under s. 8(1)(h.1) in respect of his substitute teaching job. D'Auray J. found that neither the res judicata doctrine nor issue estoppel could block the Minister from denying the taxpayer's s. 8(1)(h.1) deductions in subsequent years. Res judicata cannot apply between appeals involving different taxation years because each taxation year is a different cause of action.
Issue estoppel did not apply because the Minister had new evidence (a witness for the school board). D'Auray J. noted that, "since in income tax appeals we often deal with recurring issues," it would be inappropriate to apply issue estoppel to prevent the Minister (or the taxpayer) from introducing new evidence simply because a deduction was allowed or disallowed previously (para. 80).