659.6  Proof of malice.
  In actions for slander or libel, an unproved allegation of the truth of the matter charged shall not be deemed proof of malice, unless the jury on the whole case finds that such defense was made with malicious intent.
[R60, §2929; C73, §2682; C97, §3593; C24, 27, 31, 35, 39, §12416; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §659.6]