An administrative hearing need not be conducted according to the rules of procedure and evidence used in civil trials. Instead, any relevant evidence may be considered if it is the sort of evidence on which responsible persons are accustomed to rely in the conduct of serious affairs. (Gov. Code, § 11513(c).) So, here the department’s hearing officer did not err in admitting expert testimony from the department’s witnesses even though not designated as experts. Nor did the department deprive the defendant of a fair hearing even if it was in part motivated to bring the administrative enforcement proceeding because it believed that the defendant was in some sense responsible for the death of a child. Ulterior motives are no reason to reverse administrative decisions that are supported by substantial evidence on the grounds stated for the decision.