The public interest defence: how it works and how courts have applied it

The public interest defence is the most significant addition to Australian defamation law since the uniform defamation legislation began in 2006. Introduced in 2021 as s 29A of the Defamation Act 2005 (NSW) and its counterparts, it protects a publisher who gets something wrong, provided the subject was one of public interest and the publisher reasonably believed that publishing was in the public interest.

The defence was designed to give responsible reporting on matters of public concern a protection that the statutory qualified privilege defence in s 30 had rarely delivered. Five years on, three trial decisions have considered the defence in detail, and only one upheld it. This article explains the elements, the factors the court considers, how the decided cases have approached it, and what it means for publishers and the people they write about.

Origins

Section 29A is modelled on s 4 of the Defamation Act 2013 (UK), which replaced the common law “Reynolds” defence of responsible journalism in England and Wales. In Russell v Australian Broadcasting Corporation (No 3), the first Australian decision to consider s 29A, Lee J noted that the Explanatory Note describes the Australian provision as the progeny of the UK section, and reviewed the English authorities on it, including Serafin v Malkiewicz. His Honour cautioned, however, that English interpretations should not be imported without regard to the different wording of s 29A, which lists specific factors but does not contain the UK provision’s express allowance for editorial judgment.¹

The Australian section was approved by the Council of Attorneys General as part of the Stage 1 reforms and commenced in NSW, Victoria, Queensland, South Australia and the ACT on 1 July 2021, in Tasmania on 12 November 2021 and in the Northern Territory on 11 August 2025.²

The elements

Section 29A(1) provides that it is a defence if the defendant proves that the matter concerns an issue of public interest and that the defendant reasonably believed that the publication of the matter was in the public interest.³ Section 29A(2) requires the court to take into account all of the circumstances of the case.³

The courts have unpacked these two statutory limbs into three questions. In Al Muderis v Nine Network Australia Pty Ltd, Abraham J summarised them: first, the matter must concern an issue of public interest, which is assessed objectively; second, the publisher must have actually believed that publication was in the public interest, which requires evidence that the publisher turned its mind to the issue and held that belief, because “ex post rationalisations are not enough”; and third, that belief must have been reasonable.⁴

The third question is where most of the argument happens. Abraham J described it as whether a reasonable person standing in the defendant’s shoes, possessing the information the defendant possessed at the time, would have held that belief.⁴ An honest and reasonable belief in the truth of what is published is an important part of the assessment, but that is not the same as asking whether the allegations were actually true, because “public interest journalism does not pretend to be a form of fact finding that is functionally equivalent to the judicial process”.⁴

The reasonableness enquiry is directed to the belief itself, not to the publisher’s conduct as such. Conduct is nonetheless often the clearest evidence of what the publisher knew and believed.⁴ That distinguishes the defence from s 30, where the question is whether the conduct in publishing was reasonable.

The factors

Section 29A(3) lists factors the court may take into account to the extent it considers them applicable. In plain terms they are:

• how serious the defamatory imputation is;
• whether the publication distinguishes between suspicions, allegations and proven facts;
• whether the matter relates to the person’s public functions or activities;
• whether it was in the public interest to publish quickly;
• the sources of the information and their integrity, including whether they were anonymous;
• whether a good reason existed to keep a source confidential;
• whether the publication contained the person’s side of the story, or a reasonable attempt was made to obtain and publish a response (unless that was not possible or practicable);
• what other steps were taken to verify the information; and
• the importance of freedom of expression in discussing issues of public interest.³

Section 29A(4) makes clear that the court is not required to consider every factor and is not limited to them.³ Abraham J in Al Muderis said the factors “should not be treated as a checklist”, and that flaws in a publication or in the publisher’s process will not necessarily defeat the defence; the statute does not require journalists to “do everything right”.⁴ Where a trial is by jury, s 29A(5) gives the jury, not the judge, the task of deciding whether the defence is established.³

Who can use it

Nothing in s 29A confines the defence to professional journalists or media organisations. Any defendant can plead it: a community campaigner, a whistleblower, a blogger, a politician, a reviewer. Deeming v Pesutto (No 3), decided under the materially identical Victorian provision, illustrates that a politician commenting publicly on a colleague can plead it, although in that case the defence failed.⁵

The practical qualification is evidentiary. The defendant must prove a contemporaneous belief that publishing was in the public interest and show why that belief was reasonable on the information then held. A publisher with no notes, no verification steps and no attempt to seek a response will struggle to prove either.

How the defence differs from qualified privilege

The common law defence of qualified privilege requires a reciprocal duty or interest between publisher and recipient and is rarely available for publication to the world at large. The extended category recognised in Lange v Australian Broadcasting Corporation covers government and political matter published to the public, but only where the publisher’s conduct was reasonable, which as a general rule requires reasonable grounds to believe the imputation true, proper verification and a request for the plaintiff’s response.⁶

The statutory s 30 defence requires the recipient to have an interest or apparent interest in the subject and the publisher’s conduct to be reasonable. Since 2021, s 30(3B) states that public interest is not required for s 30.⁷ Section 29A inverts that: public interest in the subject is the gateway, the audience can be the general public, and the focus shifts from the quality of the conduct to the reasonableness of the publisher’s belief.

A practical point follows. Before 1 July 2021 the s 30 factors included public interest, sources and the plaintiff’s side of the story. Those factors were moved into s 29A, and the 2021 version of s 30 lists only five factors. A defendant whose publication postdates the amendments and who wants credit for careful verification of a story on a matter of public concern will usually plead s 29A, often alongside s 30 and the common law.

The decisions so far

Russell v ABC (No 3) [2023] FCA 1223

The first decision concerned ABC reports linking a former commando officer and his platoon to alleged killings in Afghanistan and to a criminal investigation. Lee J accepted that the respondents subjectively believed publication was in the public interest, but held the belief was not reasonable.¹ The journalist’s main source had repeatedly described his recollection as “fuzzy”; potential corroborating witnesses were not pursued in any meaningful way; a freedom of information response was presented as confirming an investigation into the platoon when it did not safely support that; the articles failed to distinguish allegation from established fact; and the haste to publish was driven significantly by a wish to vindicate earlier reporting rather than by any urgent public need.¹ The plaintiff was not told that the new article would repeat the earlier allegations, so he was not given a properly informed opportunity to respond.¹ Damages of $390,000 were awarded.¹⁷

Deeming v Pesutto (No 3) [2024] FCA 1430

The case was decided under the Defamation Act 2005 (Vic), whose s 29A is in the same terms as the NSW section. The then Victorian Opposition Leader published a media release, gave interviews and circulated an expulsion motion and dossier about a member of his party room after she attended a rally outside the Victorian Parliament on the same day as a group of neo Nazis performed Nazi salutes nearby. The plaintiff conceded that each publication concerned an issue of public interest, and O’Callaghan J found that the defendant subjectively believed publication was in the public interest.⁵ The defence failed on reasonableness. He did not take care with his language or ensure that the factual assertions had a proper foundation; he had material indicating that the people he linked to Nazism were not Nazi sympathisers; he omitted exculpatory material; he did not include the plaintiff’s denials; and the perceived urgency was driven more by political damage control than by any immediate need for the public to know.⁵ The Lange defence and honest opinion also failed and the plaintiff was awarded $300,000.⁵

Al Muderis v Nine Network Australia Pty Ltd [2025] FCA 909

The first success came in August 2025. A prominent orthopaedic surgeon sued over a 60 Minutes program, articles in The Sydney Morning Herald and The Age, and a video, published in September 2022, concerning patient experiences of osseointegration surgery. After a 65 day trial, Abraham J found that the respondents had established both contextual truth and the s 29A defence for every publication in which imputations were conveyed.⁴

On s 29A, her Honour accepted that each journalist held the requisite subjective belief, and then assessed its reasonableness against all of the information gathered in the investigation.⁴ There was a cohort of patients with negative experiences that shared significant similarities, the public coverage of the surgeon to that point had been positive, and the journalists identified the public interest as informing the public, especially prospective patients, of the other experiences.⁴ The journalists spoke to a broad range of sources, reviewed extensive documents and excluded allegations they considered insufficiently supported. Her Honour was satisfied that their beliefs were objectively reasonable and that the defence was established.⁴ She also held that the journalists maintained a reasonable belief that the publications remained in the public interest in the period after first publication.⁴

The plaintiff has appealed to the Full Court of the Federal Court. The appeal challenges, among other things, the findings on subjective belief and its reasonableness, and the rulings that protected confidential sources.⁸ Until the Full Court decides the appeal, the trial judgment is the only decision in which the defence has succeeded, and its reasoning remains subject to the outcome of that appeal.

Timing and transitional rules

Section 29A applies only to matter published after the amendments commenced in the relevant jurisdiction. The transitional provisions in Sch 4 of the NSW Act provide that the 2020 amendments apply only to the publication of defamatory matter after the commencement of the amendments.⁹ That is why Lehrmann v Network Ten Pty Ltd, which concerned a broadcast in February 2021, was decided on the pre 2021 version of s 30 rather than s 29A.¹⁰ The Full Court dismissed Mr Lehrmann’s appeal in December 2025 without needing to decide the qualified privilege contentions, but it observed that reasonableness under s 30 is assessed on what the publisher knew and did at the time of publication, not on the premise that the truth defence later succeeded or failed, and that a judge may take account of the handling of the broadcast as a whole when assessing that conduct.¹⁶ Those observations concern s 30; nothing in the Full Court’s reasons addresses s 29A directly. For continuing online publications, each download after commencement is a fresh publication, so the defence can be available for the post commencement period even where the material first appeared earlier.

Differences between jurisdictions

Western Australia has not adopted the Stage 1 reforms, so a publication governed by WA law under the choice of law rule in s 11 has no public interest defence. The defendant is left with the common law, Lange and the unamended s 30, which still includes public interest among its factors.¹⁵

Practical lessons

The three decisions point the same way. Publishers who want the protection of s 29A should be able to prove, from records made at the time, that they considered why publication was in the public interest; that they distinguished allegation from fact in the published words; that they tested their sources and pursued obvious lines of verification; that they put the substance of the allegations to the person concerned with enough information and time to respond, and reported the response; and that any urgency was genuine rather than competitive or self serving. Tone matters too: Deeming turned partly on language that went further than the material supported.

For people who are the subject of such publications, the decisions show that the defence is not a shield for sloppy or partisan work. They also show that the plaintiff’s own response to pre publication enquiries can become important evidence about what the publisher knew.

Getting advice

Whether s 29A is available turns on what the publisher knew and did before publishing, so the evidence needs to be gathered early and preserved. Anyone considering a claim or facing one over a publication on a matter of public concern should obtain advice on the transitional rules, the choice of law and the strength of the belief evidence before the pleadings are settled.