"Now when Festus had come to the province, after three days he went up from Caesarea to Jerusalem. Then the high priest and the chief men of the Jews informed him against Paul; and they petitioned him, asking a favor against him, that he would summon him to Jerusalem--while they lay in ambush along the road to kill him. But Festus answered that Paul should be kept at Caesarea, and that he himself was going there shortly. 'Therefore,' he said, 'let those who have authority among you go down with me and accuse this man, to see if there is any fault in him.' And when he had remained among them more than ten days, he went down to Caesarea." (Acts 25:1-6).
Festus came to power in approximately A.D. 60 after Nero recalled Felix. He would now have to deal with one of the "problems" Felix had left behind--the apostle Paul. As Festus is getting accustomed to the province and his new responsibilities, the Jewish religious leaders are quick to speak to him strongly against Paul. They ask Festus for a similar favor they had made to Felix, namely, that he would bring Paul to Jerusalem (so they could secretly plan to kill him along the way). The favor is not granted, but Festus invites them to travel, as he is about to, to Caesarea where he would be willing to hear their case against Paul. After spending another 10 days in Jerusalem, Festus makes the journey to Caesarea.
"And the next day, sitting on the judgment seat, he commanded Paul to be brought. When he had come, the Jews who had come down from Jerusalem stood about and laid many serious complaints against Paul, which they could not prove, while he answered for himself, 'Neither against the law of the Jews, nor against the temple, nor against Caesar have I offended in anything at all.' But Festus, wanting to do the Jews a favor, answered Paul and said, 'Are you willing to go up to Jerusalem and there be judged before me concerning these things?' So Paul said, 'I stand at Caesar's judgment seat, where I ought to be judged. To the Jews I have done no wrong, as you very well know. For if I am an offender, or have committed anything deserving of death, I do not object to dying; but if there is nothing in these things of which these men accuse me, no one can deliver me to them. I appeal to Caesar.' Then Festus, when he had conferred with the council, answered, 'You have appealed to Caesar? To Caesar you shall go!'" (Acts 25:6-12).
There is no indication that Paul had any forewarning about this matter. Of course, he didn't need any time to prepare himself to address Festus and his accusers. He would simply speak the truth with God guiding his speech (cf. Matt. 10:17-20). As Festus sat on the judgment seat, the Jews who had come from Jerusalem blasted Paul with many false accusations, none of which they could prove. Paul, after being a prisoner for two years now, remained firm in his convictions. He affirmed that he had done nothing wrong against either Jewish or Roman law, and he had not done anything inappropriate in the temple either. He was innocent, and Festus knew it.
However, Festus, in an effort to endear himself to the Jews did not release Paul (which would have been the proper thing to do), but instead inquired if Paul would be willing to be put on trial before him in Jerusalem (as if to imply that Festus' presence there would ensure justice). Although the new governor may be unaware of the evil plotting of the Jews (i.e., to kill Paul in transit), the apostle was no fool. No doubt he remembered the initial plot against him that was exposed by his nephew (cf. Acts 23:16). Besides, Paul has no interest in going back to Jerusalem at this time. The Lord told him that he would be going to Rome, and that's what he desires, too. Thus, Paul replied - "I stand at Caesar's judgment seat, where I ought to be judged. To the Jews I have done no wrong, as you very well know." Paul went on to acknowledge that if he had truly done something wrong, he would not resist the proper punishment. In fact, his words here show us clearly that even today in the Christian dispensation there are some crimes that deserve nothing less than death as punishment (cf. Rom. 13:4).
Since Paul has no confidence in Festus to do the right thing, he then requested that his case be transferred to the emperor himself instead of back to Jerusalem where the unbelieving Jews so bitterly hated him. It was Paul's right as a Roman citizen to appeal to Caesar, and Festus did not deprive him of that right.