Mr Agius appealed against a decision finding him guilty of publishing an article in 1998 that claimed inquiries by the PN were aimed at uncovering something that someone wanted to hide and Mr Saliba was named as one of the people who should be investigated.
In its judgement, the court said the article was not fair comment because it alleged that Mr Saliba had done something wrong, an allegation that had not been substantiated.
Mr Justice Tonio Mallia presided over the court.