How have courts interpreted the defence of the due diligence defence?

Each case has to be decided on its own facts. As outlined by Bowman T.C.J. in Cloutier v. M.N.R.[5] the analysis of the due diligence defence is a question of fact: The question therefore becomes one of fact and the court must to the extent possible attempt to determine what a reasonably prudent person ought to have done and could have done at the time in comparable circumstances. Attempts by courts to conjure up the hypothetical reasonable person have not always been an unqualified success. Tests have been developed, refined and repeated in order to give the process the appearance of rationality and objectivity but ultimately the judge deciding the matter must apply his own concepts of common sense and fairness.