Even in a case in which the court applies the de novo standard of review to a petition for administrative mandamus, the court reviews for abuse of discretion the administrative agency’s refusal to consider new evidence presented after the ALJ’s decision. Here, the court reverses, finding an abuse of discretion in the Appeals Board’s refusal to consider a belated declaration which showed that the ALJ had gotten the chronology of events wrong. The error was critical because the ALJ found, as a result, that the second disciplinary complaint arose after the employee had been warned, given further training and was on probation. The new evidence showed that the second complaint preceded warning, training and probation. While the employee did not have much of an excuse for the late presentation of the evidence, its importance may have escaped him until the ALJ’s ruling made it apparent.