jon.pierre
Its been some time since I practiced law (even longer since I had anything to do with defamation) but essentially defamation (its all defamation these days as the distinction between slander and libel has gone) is a statement that lowers a pesons reputation in the eyes of other people.
Its not enough that the subject of the statement feels that their reputation has been lowered but the feeling of other people towards that person that is important.
In most Australian jurisdictions truth alone is not a defence. There must be an overriding benefit to the public in the statement being published. I believe the only exception to that is in New South Wales (the defamation capital in Australia if not the world).
The courts have balanced the right of freedom of speech against the right to reputation and for some time the right to reputation was given precedence although the pendulum may be swinging the other way again given some recent High Court cases.
Hope this helps and if there are any practicing lawyers out there please feel free to correct me if I'm wrong. As I said its been some years now.