{This man might have been set at liberty} (Apolelusthai
edunato ho anthr(9370)os houtos). Conclusion of the second class
condition (determined as unfulfilled) without an as in  24:19 
because of edunato (verb of possibility, Robertson, _Grammar_,
p. 1014). Note perfect passive infinitive apolelusthai from
apolu(935c). He certainly "could have been set free." Why was it not
done? {If he had not appealed unto Caesar} (ei m(8820)epekekl(8874)o
Kaisara). Condition of the second class with the past perfect
middle indicative (_op. cit._, p. 1015) of epikale(935c) (cf.
 25:11f. ). But Paul _only_ appealed to Caesar after Festus had
tried to shift him back to Jerusalem and had refused to set him
free in Caesarea. Festus comes out with no honour in the case.
Since Agrippa was a favourite at court perhaps Festus would be
willing to write favourably to Caesar.