I arbitrated a case awhile back where the case looked airtight for the employer to prove cause based on the evidence that the investigator had found. However, for various reasons the employer did not or could not present the same evidence at the arbitration and they were unable to prove just cause.
On the other hand, plaintiffs sometimes want to advance the argument that the investigation was faulty or negligent. Presumably this is to advance claim for punitive damages. If they do this the report does go into evidence and can be considered by the Court . Although this report should not be considered as evidence of the facts set out in the report, it does get read by the judge and may well affect the judges’ view of the case.
I think in most cases plaintiffs are better off trying to keep the entire report out of evidence and forcing the employer to prove every point of the just cause allegation by live witnesses and admissible documents .
However the Court found that absent a contractual obligation to do so, there is no duty of procedural fairness before terminating someone for cause and furthermore the employer can properly rely on additional evidence that they obtained after the dismissal.
The issue is not whether the employer made a reasonable decision about just cause. The issue is whether the Court finds that the employer has proven on the balance of probabilities that the plaintiff committed an act of just cause.
Thus where the employer conducts no investigation or a poor investigation but the Court finds the employee committed theft, just cause has been proven.
Where the employer conducts a perfect investigation which finds the employee guilty of theft but the Court disagrees with that conclusion, the employee will succeed.
Remember an investigation report is itself is NOT evidence of the matters set out in report. Each of those facts must be independently proven in Court.