In Montemayor v. Bundalian,^[21] this Court laid down the guidelines for the judicial review of decisions rendered by administrative agencies in the exercise of their quasi-judicial powers, as follows:

First, the burden is on the complainant to prove by substantial evidence the allegations in his complaint. Substantial evidence is more than a mere scintilla of evidence.  It means such relevant evidence as a reasonable mind might accept as adequate to support a conclusion, even if other minds equally reasonable might conceivably opine otherwise.  Second, in reviewing administrative decisions of the executive branch of the government, the findings of facts made therein are to be respected so long as they are supported by substantial evidence.  Hence, it is not for the reviewing court to weigh the conflicting evidence, determine the credibility of witnesses, or otherwise substitute its judgment for that of the administrative agency with respect to the sufficiency of evidence.

Third, administrative decisions in matters within the executive jurisdiction can only be set aside on proof of gross abuse of discretion, fraud, or error of law.  These principles negate the power of the reviewing court to re-examine the sufficiency of the evidence in an administrative case as if originally instituted therein, and do not authorize the court to receive additional evidence that was not submitted to the administrative agency concerned.  [emphases ours]