Five years ago this month, the serious harm element entered Australian defamation law with little fanfare. Section 10A of the uniform Defamation Act 2005 — commencing 1 July 2021 in New South Wales, Victoria, Queensland, South Australia and the ACT — required, for the first time, that a plaintiff prove the publication has caused or is likely to cause serious harm to their reputation before anything else in the case matters. You can read the full text of s 10A and our practical guide here.
Half a decade on, the verdict is in: no provision has done more to reshape who sues, who settles, and who wins.
Evolution or Revolution?
In a new article in the University of New South Wales Law Journal, Professor David Rolph — author of the leading Australian text on defamation — poses the question directly: is serious harm an evolution or a revolution? His answer is revolution. By its terms, s 10A impliedly abolishes the centuries-old presumption of damage to reputation. Harm is no longer presumed from publication; it must be proved, as a matter going to liability, on actual evidence of actual impact (D Rolph, ‘Serious Harm to Reputation: Evolution or Revolution?’ (2026) 49(2) UNSW Law Journal 335).
That academic framing matches exactly what we see in practice. The threshold question in almost every matter that crosses our desk is no longer “is it defamatory?” but “can serious harm be proved?”
How the Courts Have Applied It
The early decisions established the machinery: serious harm is determined by the judicial officer, not a jury, and can be — and frequently is — determined before trial, with proceedings dismissed if the element is not established. The English experience under the equivalent provision informed the Australian approach: harm must be assessed by reference to actual facts about the publication’s impact, not merely the meaning of the words.
In Singh v Singh [2025] FCA 1531 — a matter in which this firm acted — the Federal Court engaged in a detailed assessment of what serious harm requires in a contested factual setting, and the decision has become a key reference point on the evidence that carries the element.
And this month, s 10A decided the highest-profile social-media defamation case in the country. In MacInnes v Wilson, the Federal Court dismissed the actor’s claim against Rebel Wilson in its entirety — not on a defence, but at the threshold: the applicant “failed to establish that the publications have caused or were likely to cause serious harm.” Costs followed. An appeal to the Full Court was filed the next day, and serious harm will be the central battleground there too.
The Five-Year Scoreboard
Trivial claims are being filtered out. The neighbourhood spat, the single hurtful Facebook comment seen by a dozen people — claims like these now rarely survive, and prospective plaintiffs are told so early. That is precisely what the reform intended.
Evidence has moved to the front of the case. The material that once mattered only to damages — extent of publication, the grapevine effect, identifiable people whose view of the plaintiff changed, lost work — is now the price of admission. Serious claims are built from day one around that proof, often starting with a well-drafted concerns notice that puts the harm evidence on the record.
Corporations face a double gate. An excluded corporation must show the publication caused, or is likely to cause, serious financial loss — reputational bruising is not enough.
The uniform scheme has caught up. Queensland’s Stage 2 amendments, adopted through the Defamation and Other Legislation Amendment Bill 2025, brought that state into line on the later reforms — but s 10A itself has operated uniformly across the Stage 1 jurisdictions since 2021, so the serious harm threshold applies with equal force whether the publication was read in Sydney, Melbourne or Brisbane.
What the Next Five Years Hold
The MacInnes appeal will give the Full Court of the Federal Court its most significant opportunity yet to define how serious harm is assessed where a publication reaches millions — including how audience scale interacts with actual, provable impact. Whichever way it falls, the appeal will shape pleading and evidence strategy for every substantial social-media defamation claim in the country.
For anyone weighing a claim today, the practical lesson of five years is simple: the cases that succeed are the ones where serious harm is treated as the case, not a box to tick. If you have been seriously defamed, the evidence of that harm exists — and capturing it early, properly, is where we start.
Matrix Legal acts exclusively in defamation matters, Australia-wide. Call 1800 950 627 for a free case assessment.
Frequently Asked Questions
When did the serious harm element commence?
1 July 2021, in the Stage 1 jurisdictions (NSW, Victoria, Queensland, South Australia, the ACT), with others following. July 2026 marks five years of its operation.
Has it made claims harder to bring?
Yes — deliberately. Claims without evidence of real reputational damage can now be dismissed at the threshold by the judge, often before trial, as occurred in MacInnes v Wilson.
What evidence proves serious harm?
Extent and spread of publication, identifiable people whose opinion of you changed, lost work or clients, and the gravity of what was said. Read our full s 10A guide for the detail.
Mark Stanarevic is the principal of Matrix Legal, Australia’s specialist defamation law firm. This article is general information, not legal advice.