Forest I think Graham has answered the question briefly in the past regarding identifying posters.

My impression is that it would take a court order, eg the litigant would have to establish to the courts that there may be a case to answer. Not really suitable for those who know that they don't have a case but rely on the threat of action to silence others.

From my limited reading on the topic an administrators liability is impacted by their editorial approach. If on most issues the administrators maintain a light touch then they are less at risk than those who routinely use editorial power but who also fail to act in a particular case.

In my view threats of legal action which are not clearly justified and/or followed through with should lead to cancelling of access to the site. Such threats are designed to intimidate other users and in some cases are probably all to successfull. I don't know if doing so would breach any laws though. Such a policy could be a minefield in itself.

Some of the forum's User Conduct prohibitions may be relevant
http://www.onlineopinion.com.au/display.asp?page=legal
"You must not up-load, post, transmit or otherwise make available through this site any material which:

- violates or infringes the rights of others (including their privacy and publicity rights).
- is unlawful, threatening, abusive, defamatory, invasive of privacy, vulgar, obscene, profane or which may harass or cause distress or inconvenience to, or incite hatred of, any person.
- encourages conduct that would constitute a criminal offence, give rise to civil liability or otherwise violate any law.
- restricts or inhibits any other user from using or enjoying this site.
- affects the functionality or operation of this site or its servers or the functionality or operation of any users' computer systems (for example, by transmitting a computer virus or other harmful component, whether or not knowingly).
- breaches any standards, content requirements or codes promulgated by any relevant authority, including authorities which require us to take remedial action under any applicable industry code. "

R0bert