Julian Assange’s threat to sue Prime Minister Julia Gillard for defamation could be nothing more than a publicity stunt, with experts telling Crikey the WikiLeaks founder may have left it too late to bring legal action.

Assange told activist group GetUp! he could sue Gillard for comments made in 2010, when she labelled the WikiLeaks publication of classified US diplomatic cables as “illegal” and “grossly irresponsible”. He says he has hired lawyers in Sydney and plans to bring the case to court.

Defamation expert Mark Pearson reckons it’s “poor form” by Assange. Pearson, author of Blogging and Tweeting Without Getting Sued, told Crikey: “I think it’s particularly out of order for journalists and free expression advocates to use defamation as a means of chilling debate.”

Pearson and other defamation experts say the case is unlikely to be heard though, because under Australian law a defamation suit must be brought within 12 months of the publication of the defamatory statement.

Assange told GetUp!’s Rohan Wenn he thought he would be able to gain an extension on the 12-month period because of his house arrest in the UK and confinement to the Ecuadorian embassy in London. Cass Matthews, a media law expert at the University of Melbourne, says that will be “difficult” and will depend on Assange’s circumstances within the year following the PM’s statement.

Pearson agrees, saying the issue hasn’t been tested in Australia before. The provision is designed for cases where it may take time to find the source of a rumour, which is not the case with Assange. “The usual criteria is when the comments have only just been brought to the attention of the plaintiff,” according to Pearson.

Professor Andrew Kenyon, director of the Centre of Media and Communications Law, told Crikey repeated publication of the comments could be an avenue for gaining an extension (Assange has said he won’t sue any media outlet that has republished Gillard’s comment).

Wenn conducted the interview with Assange. “Julian made it perfectly clear that his beef is with the Prime Minister and not with any media outlets,” he told Crikey.

If Assange were to gain an extension in order to bring the case, law experts believe proving the statement is defamatory would be simple, but Gillard may have defences available to her.

Matthews believes qualified privilege would be the strongest. “She would need to prove that she has acted reasonably — that would mean that she has researched what she is saying. If that was simply a mistake or it was not based on proper material then she would not have that defence,” she said.

Pearson says it’s unlikely the PM would ever need to argue her case. “People threaten defamation action but very few of those threats actually culminate in action and often the threat is a publicity stunt,” he said.

Assange has high hopes for the case, according to Wenn, with discussions taking place in London for more than 12 months: “He thinks that once the Prime Minister has to acknowledge that WikiLeaks hasn’t done anything illegal, then it’s like ‘why aren’t you helping the guy?'”

Pearson questioned Assange’s motivation for threatening legal action when he faces more pressing legal issues: “I really think it’s a distraction from the main problems he faces. You really think he would be putting all his efforts into the defence of the Swedish allegations and over concerns of his extradition to the US.”