Albert Barnes on John 18:30

If he were not a malefactor. A violator of the law. If we had not determined that he was such, and was worthy of death, Mt 26:66. From this it appears that they did not deliver him up to be tried, but hoped that Pilate would at once give sentence that he should be executed according to their request. It is probable that in ordinary cases the Roman governor was not accustomed to make very strict inquiry into the justice of the sentence. The Jewish Sanhedrim tried causes and pronounced sentence, and the sentence was usually approved by the governor; but in this case Pilate, evidently contrary to their expectations, proceeded himself to rehear and retry the cause. He had doubtless heard of the miracles of Jesus. He seems to have been strongly prepossessed with the belief of his innocence. He knew that they had delivered him from mere envy (Mt 27:18), and hence he inquired of them the nature of the case, and the kind of charge which they expected to substantiate against him.