How defamation law works on social media in Australia

One bad review, a single comment thread, or a tagged post can reach thousands of people within hours, and it never really goes away. When the post makes a false statement that damages your reputation, defamation law gives you a route to a correction, an apology, and compensation, but only if you work within a strict framework of steps and time limits.

Defamation on social media is not a separate area of law. It is the ordinary law of defamation applied to posts, comments, reviews, and shares. Every Australian state and territory operates the same uniform legislation, based on the Defamation Act 2005 (NSW), and reforms in 2021 and 2023 were aimed squarely at online publication: a new serious harm requirement, a one-year time limit, and statutory protections for digital platforms. This guide explains how the scheme actually works: who can sue, who can be held responsible, the compulsory steps before court, the defences available, and the remedies a successful claim produces.

A social media defamation claim involves a small cast of parties, each with a distinct role:

The aggrieved person: the individual or business whose reputation is said to be harmed. They bring the claim.
The poster: the person who wrote the post, comment, review, or reply. They are the primary publisher.
The page operator: the person or business that runs the page, group, or profile where the material appears. As we will see, they can be a publisher too, even of comments they did not write.
The platform: the company operating the service, such as Facebook, Instagram, TikTok, X, LinkedIn, Google, or Reddit.
The court: defamation is a civil claim heard in state and territory courts, not by a regulator or the police.

The single most important feature of the scheme is that publication is a strict liability concept. You can be a publisher without intending to defame anyone, which is why so many social media disputes involve people who "did not mean any harm". That fact drives everything else in this article.

What makes a post defamatory: the elements of a claim

A claim succeeds only if the person suing establishes four elements:

Defamatory matter: The post must convey an imputation, a meaning, that would tend to lower the person in the estimation of ordinary reasonable members of the community. Implied meanings, jokes, and innuendo count, and a post can be defamatory without naming anyone.
Identification: The ordinary reasonable reader must understand the post to refer to the plaintiff, whether by name, photo, description, business name, or tag.
Publication: The matter must be communicated to at least one person other than the person defamed. A post uploaded to a public page is published when it becomes accessible to others, and every share, retweet, or repost is a fresh publication to a fresh audience.
Serious harm: Since the 2021 reforms, s 10A of the Defamation Act 2005 (NSW) requires proof that the publication caused, or is likely to cause, serious harm to reputation. For a small business that qualifies as an excluded corporation, serious harm means serious financial loss. A judge, not a jury, decides this threshold and can do so before trial, dismissing claims that do not meet it.

Defamation is overwhelmingly a civil matter, so the police are not the route to a remedy. A handful of states also make the most serious cases criminal offences, but prosecutions are extremely rare, and the practical path for a defamed business or individual runs through the civil scheme.

Who can sue: individuals and the small business exception

Any individual can sue for defamation of their own reputation, regardless of whether they run a business.

Companies are different. Under s 9 of the Defamation Act 2005 (NSW), a corporation has no cause of action unless it was an "excluded corporation" at the time of the publication. A corporation is excluded if either of these applies:

Not-for-profit: the objects for which it is formed do not include obtaining financial gain for its members or corporators, or
Fewer than 10 employees: it has fewer than 10 employees and is not an associated entity of another corporation,

and in either case it must not be a public body. Part-time employees are counted as a fraction of a full-time equivalent.

So a proprietary company with a handful of staff can sue over a damaging post or review. A larger company cannot sue in its own name; its remedy runs through the individuals associated with it, who can sue for defamation of themselves even where the same matter also defames the company (s 9(5)). Note also that claims die with the person: no cause of action exists for defamation of a deceased person, so family members cannot sue over posts about someone who has died (s 10).

Who can be sued: posters, page operators, and platforms

The poster

The poster is the primary publisher and the obvious target, but posters are often anonymous, and identifying them usually requires court orders compelling the platform to hand over account details. Platforms generally will not volunteer that information, and this is one of the first places a lawyer earns their fee.

The page operator

The page operator can be liable for material they did not write. In Fairfax Media Publications Pty Ltd v Voller [2021] HCA 27, the High Court held that media companies operating public Facebook pages were publishers of defamatory comments posted by third parties under their posts. The companies invited and encouraged comment, had the capacity to moderate it, and benefited from the engagement, and that was enough. Intention to defame was not required. The same reasoning applies to any business that runs a public page or group where comments are invited: you can be held responsible for what others post on your page, and your moderation settings, filters, and deletion practices are part of the picture.

Search engines and platforms

Search engines and platforms sit in a different position. In Google LLC v Defteros [2022] HCA 27, the High Court held that Google was not a publisher of the content of web pages to which its search results hyperlinked, because its role was limited to providing an automated search tool. The position is now also codified. Amendments made by the Defamation Amendment Act 2023 (NSW) inserted a new Division 2A into the Defamation Act 2005 (NSW):

s 10C exempts a digital intermediary from liability where its role in the publication was limited to providing a caching, conduit, or storage service, and it did not initiate the publication, select recipients, encourage the poster, edit the content, or promote the matter;
s 10D exempts search engine providers for automated search results and hyperlinks, but not where results are promoted or prioritised because of a payment;
s 10E requires the court to determine the exemption as soon as practicable before trial, and allows proceedings to be dismissed if it is established.

The practical result is that the person who runs the page is the realistic target, not the platform hosting it.

The compulsory first step: concerns notices and offers to make amends

Before any defamation proceedings can be commenced, the aggrieved person must give the proposed defendant a concerns notice, and the response period must have elapsed (ss 12A and 12B of the Defamation Act 2005 (NSW)). The notice must:

be in writing,
specify the location where the matter can be accessed, for example the webpage address,
set out the defamatory imputations the person considers the matter carries,
set out the serious harm, or for an excluded corporation the serious financial loss, said to have been caused or likely to be caused, and
be accompanied by a copy of the matter where practicable.

The imputations particularised in the notice matter twice: the plaintiff cannot later rely on imputations that were not particularised, or that are not substantially the same.

Once a concerns notice is given, the publisher has 28 days to make an offer to make amends (s 14). The offer can include a correction, an apology, removal of the material, and compensation. If the aggrieved person unreasonably refuses a reasonable offer, the publisher has a complete defence to the claim (s 18). This is the scheme's pressure valve, and it is why most social media defamation disputes resolve in the first month rather than in court.

The time limits are tight. Under s 14B of the Limitation Act 1969 (NSW), an action must be commenced within one year of publication, and for matter in electronic form the date of publication is the day it was first uploaded for access. A concerns notice given within 56 days before the one-year period expires extends the period by 56 days minus the days remaining. The court can extend the period to up to three years from publication if it is just and reasonable to do so (s 56A), but that is a discretionary application, not a safety net. The single publication rule in s 14C means that republishing substantially the same matter does not restart the clock against the original publisher, unless the manner of the later publication is materially different. A share or repost by someone else, however, is a publication by that person, with its own clock.

The defences to a defamation claim

The uniform laws provide a suite of defences, each turning on its own facts:

Truth (justification): Under s 25, it is a defence if the defamatory imputations carried by the matter are substantially true. If the statement is true, there is no liability, however damaging it is.
Contextual truth: Under s 26, the defence succeeds where the matter also carried other imputations that are substantially true, and those true imputations mean the imputations complained of do not further harm the plaintiff's reputation.
Honest opinion: Under s 31, a defence exists where the matter was an expression of opinion rather than a statement of fact, the opinion related to a matter of public interest, and it was based on proper material. Writing "I think" or "in my opinion" does not convert a factual assertion into protected opinion.
Public interest: Since the 2021 reforms, s 29A provides a defence where the matter concerned an issue of public interest and the publisher reasonably believed the publication was in the public interest. Courts weigh the seriousness of the imputation, whether suspicions were distinguished from proven facts, the reliability of sources, and similar factors.
Innocent dissemination: Under s 32, a defence exists for a subordinate distributor who did not know, and ought not reasonably to have known, that the matter was defamatory, and whose lack of knowledge was not due to negligence. This protects genuine intermediaries, but it did not save the page operators in Voller, who invited and could moderate the comments.
Triviality: A defence exists where the circumstances of the publication were such that the plaintiff was unlikely to sustain any harm, which complements the serious harm element.
Privileges: Absolute and qualified privilege protect reports of court and parliamentary proceedings and similar publications, but they rarely apply to ordinary social media posts.

What a successful claim delivers: remedies and damages

Many matters end at the amends stage with a correction, an apology, and removal of the post, which is usually what the aggrieved person actually wants. Where proceedings run to judgment, the remedies are damages and injunctions ordering the removal of the material and restraining further publication.

Damages for non-economic loss, the harm to feelings and reputation, are capped. Section 35 of the Defamation Act 2005 (NSW) sets the maximum at $250,000, the figure that applied when the uniform laws commenced in 2005, adjusted each year for inflation, so the cap in force at the time damages are awarded is considerably higher than the original figure. The maximum is reserved for the most serious cases. Aggravated damages can be awarded on top where the defendant's conduct has made things worse, and damages must bear a rational relationship to the harm actually sustained (s 34). Exemplary or punitive damages cannot be awarded (s 37).

Economic loss is also recoverable, and for a small business it is usually the heart of the claim: the customers, contracts, or revenue lost because of the post. For an excluded corporation, serious financial loss is built into the serious harm element itself, so the two inquiries overlap.

Social media defamation claims most often go wrong in a handful of predictable ways:

"It was just my opinion": The honest opinion defence protects genuine opinion on proper material, not factual assertions prefaced with "I think". A review that asserts a business is a "scammer" or "crook" is asserting facts, not offering opinion.
The page operator who does not moderate: After Voller, inviting comment and then ignoring it is a liability posture. Businesses that run public pages should know what moderation tools they have, use them, and remove defamatory content promptly.
Deleting the evidence: Posts, comments, and reviews vanish or get edited. Screenshots of the post, its URL, the date, and the account that posted it should be taken immediately, before any takedown request, because the request itself can prompt deletion.
Missing the one-year clock: The clock runs from upload, not from when you discover the post. Content archived online for years does not extend the time to sue the original poster.
The 10-employee barrier: Companies with 10 or more employees cannot sue in their own name, so a large business attacked online must think in terms of its individual directors, founders, and spokespeople, or alternative remedies.
Escalating in the replies: A business that responds to a negative review by accusing the reviewer of dishonesty or criminal behaviour can publish a fresh defamatory statement of its own, and become the defendant rather than the plaintiff.

When you need a defamation lawyer

A lawyer is needed at the points where the scheme is unforgiving. Before sending a concerns notice, because the imputations particularised now are the imputations you can sue on later, and a defective notice can stop proceedings before they start. When responding to a notice, because the 28-day amends window is short and the decision to offer amends, and on what terms, should be strategic. When the poster is anonymous, because unmasking them requires court processes against the platform. When serious harm is contestable, because a judge can dismiss the claim before trial. And when an amends offer arrives, because refusing a reasonable offer can hand the defendant a complete defence.

Defamation is expensive when it goes wrong, but most of that cost is avoidable with early advice. Getting the first steps right, the evidence preserved, the notice properly drawn, and the serious harm question assessed, is far cheaper than repairing a blown deadline or a defective notice later.

Every part of this scheme compresses toward the first month. The evidence must be captured while the post is still live, the concerns notice must be drawn correctly before the clock runs, and the 28-day amends window is when the dispute is either settled cheaply or set on a path to court. If you are the aggrieved person, the question a lawyer should answer for you early is whether serious harm is actually provable, because a judge can dismiss a claim that fails that test before trial. If you are the poster or page operator, the cheapest exit is a reasonable offer to make amends made within the window, because an unreasonable refusal of it becomes your defence. Either way, the first month is where the value sits, and it is the point at which a few hours of legal advice is worth more than a year of proceedings.