Fifth Exception.-It is not defamation to express in good faith any opinion whatever respecting the merits of any case, civil or criminal, which has been decided by a Court of Justice, or respecting the conduct of any person as a party, witness or agent, in any such case, or respecting the character of such person, as far as his character appears in that conduct, and no further. Illustrations (a) A says- "I think Z's evidence on that trial is so contradictory that he must be stupid or dishonest." A is within this exception if he says this in good faith, inasmuch as the opinion which he expresses respects Z's character as it appears in Z's conduct as a witness, and no further. (b) But if A says- "I do not believe what Z asserted at that trial because I know him to be a man without veracity." A is not within this exception, inasmuch as the opinion which he expresses of Z's character, is an opinion not founded on Z's conduct as a witness.