Serious Harm Threshold — s 10A Defamation Act 2005

The Origins and Purpose of the Serious Harm Threshold

Before 1 July 2021, Australian defamation law was widely criticised for its imbalance: the law provided inadequate protection against serious reputational harm while simultaneously creating a chilling effect on legitimate speech by allowing technically defamatory but trivial claims to be pursued at enormous cost. The Australian Law Reform Commission and its state equivalents identified the absence of a threshold requirement as one of the key structural deficiencies in the pre-reform regime.

The serious harm threshold — s 10A of the Defamation Act 2005 — was the centrepiece of the Stage 1 reforms enacted through the Defamation Amendment Act 2020 (NSW) and equivalent legislation in Victoria, Queensland, South Australia, Western Australia, Tasmania, the ACT, and the Northern Territory. The reforms commenced operation in most jurisdictions on 1 July 2021. The provision was modelled, in significant part, on s 1 of the United Kingdom Defamation Act 2013, which introduced a similar threshold in England and Wales.

The purpose of s 10A is to filter out trivial and hypersensitive claims at an early stage, concentrating the court's resources on cases involving genuine and substantial harm to reputation. It is designed to be a meaningful threshold — not a rubber stamp — and the courts have approached it as such.

Section 10A: The Statutory Text

Section 10A of the Defamation Act 2005 (NSW) provides:

(1) It is an element of a cause of action for defamation that the publication of defamatory matter about a person has caused, or is likely to cause, serious harm to the reputation of the person.

(2) For the purposes of this section, harm to the reputation of a corporation is not serious harm unless it has caused or is likely to cause the corporation serious financial loss.

(3) For the purpose of determining whether the publication of defamatory matter about a person has caused, or is likely to cause, serious harm to the reputation of the person, the court may have regard to the following matters—
(a) the nature of the defamatory matter;
(b) the extent of publication of the defamatory matter;
(c) the circumstances in which the defamatory matter was published;
(d) any other matters the court considers relevant.

The Serious Harm Standard: What Is Required?

The statutory language — "has caused, or is likely to cause, serious harm" — establishes a two-limbed test. Harm that has already materialised by the time of the s 10A determination satisfies the first limb. Harm that has not yet materialised but that the evidence establishes is likely to occur satisfies the second limb.

The word "serious" is not defined in the Act, but the courts have drawn guidance from the English jurisprudence under the UK Defamation Act 2013 and from the general meaning of the term in legal contexts. "Serious" harm is harm that is substantial — it is not trivial, nominal, or de minimis. It is harm of a kind and degree that a reasonable person would regard as genuinely significant.

Critically, the threshold is not satisfied merely by showing that the defamatory imputations were of a grave character. A false allegation of murder would carry very serious imputations, but if the publication was made to an audience of one person who did not believe it and who told no one, the actual harm to reputation may be negligible. The seriousness of the imputations is relevant to, but not determinative of, the seriousness of the harm.

Singh v Singh: The Leading Australian Case

The most important Australian case on the serious harm threshold is Singh v Singh [2025] FCA 1531. This litigation arose from allegations made within a Sikh community network and became the principal vehicle through which Australian courts explored the meaning and application of s 10A.

The Federal Court confirmed a number of important propositions about the serious harm threshold:

1. Evidence is required. The court cannot simply infer serious harm from the nature of the defamatory imputations. The plaintiff must adduce positive evidence of harm, or evidence from which harm can be properly inferred. Assertion, without evidence, is insufficient.
2. The harm must be to reputation, not merely to feelings. While injury to feelings is relevant and may be compensated in damages, it is not by itself sufficient to satisfy the serious harm threshold. The plaintiff must demonstrate harm to their reputation — that is, to the estimation in which they are held by others — not merely to their own subjective sense of self-worth or their emotional state.
3. The extent of publication is critical. A defamatory statement that circulated only within a small group of people who were already disposed to think poorly of the plaintiff, or who did not believe the allegation, is less likely to cause serious harm than a statement that was widely published to an audience of people who were previously neutral or well-disposed toward the plaintiff.
4. Likely harm must be evidence-based. The second limb of s 10A — "likely to cause" — is not met by speculative or conjectural assertions about what harm might occur. There must be a proper evidentiary foundation for the conclusion that serious harm is likely.
5. The threshold is assessed at the time of determination, not publication. The court can take into account evidence of events after publication in assessing whether serious harm has occurred or is likely to occur.

For a detailed case note on Singh v Singh and its practical implications, see our Case Note: Singh v Singh.

The English Threshold: Guidance from the UK

Because s 10A was modelled on s 1 of the UK Defamation Act 2013, English case law provides valuable interpretive guidance. The most significant English authority is Lachaux v Independent Print Ltd [2019] UKSC 27, in which the United Kingdom Supreme Court confirmed that the serious harm threshold requires an assessment of the actual facts and evidence, not merely an evaluation of the gravity of the imputations on the face of the publication. Lord Sumption's judgment established that the threshold is a "real" requirement with "real" content — it is not satisfied merely by showing that the words, read literally, would tend to seriously lower the plaintiff's reputation.

Australian courts have expressly endorsed this approach. The serious harm threshold is not a technical obstacle but a substantive requirement that a plaintiff must satisfy by reference to evidence of real-world harm to their reputation.

Corporations and Serious Financial Loss

Section 10A(2) introduces a more onerous standard for corporations: harm to a corporation's reputation does not constitute serious harm unless it has caused, or is likely to cause, the corporation serious financial loss. This reflects the legislature's judgment that corporations, unlike individuals, can suffer reputational harm primarily in commercial terms and that the law should require proof of commercial impact before allowing costly defamation proceedings to proceed.

Not all corporations can sue for defamation. Under s 9(2) of the Defamation Act 2005, a corporation can only sue if it employs fewer than 10 persons at the time of publication and is not related to a corporation that employs 10 or more persons. This "small business" threshold excludes most large corporations from the defamation regime entirely.

For eligible small business corporations, proving serious financial loss under s 10A(2) requires concrete evidence of economic harm — lost contracts, reduced revenue, declined business enquiries, lost investment opportunities — rather than speculation about what might happen. The financial loss must itself be "serious" — a modest or temporary decline in revenue is unlikely to satisfy the threshold.

The Rush v Nationwide News Decision

The Federal Court decision in Rush v Nationwide News Pty Ltd [2019] FCA 496 — decided before the introduction of s 10A but relevant to the serious harm assessment by analogy — demonstrated the devastating reputational consequences that false allegations of serious misconduct can cause and the substantial damages that flow from such harm. In Rush, the Federal Court found that allegations of serious and inappropriate behaviour had caused profound harm to the actor Geoffrey Rush's personal and professional reputation, awarding him approximately $2.87 million in damages, including $850,000 in general damages (incorporating aggravated damages) and approximately $1.98 million in special damages for past and future economic loss. The Rush decision remains instructive on how courts assess the gravity and extent of reputational harm in high-profile cases.

Practical Implications: What Evidence Do You Need?

The serious harm threshold has fundamentally changed how defamation claims are investigated and prepared. A plaintiff contemplating defamation proceedings must, from the outset, focus on gathering evidence of serious harm. That evidence may include:

• Witness evidence — statements from people who read the defamatory material and whose view of the plaintiff was affected. This is often the most powerful evidence of actual harm to reputation.
• Statistical evidence — in online defamation cases, evidence of the number of views, shares, clicks, and comments on the defamatory publication.
• Commercial evidence — for businesses, evidence of decline in revenue, lost contracts, reduced enquiries, or cancelled bookings that are causally connected to the defamatory publication.
• Professional evidence — for professionals, evidence of lost referrals, lost employment opportunities, or damage to professional standing within the relevant field.
• Social and personal evidence — evidence of damage to personal relationships, social exclusion, or other measurable social consequences of the defamatory publication.
• Plaintiff's own evidence — the plaintiff's own account of the impact of the publication on their life, relationships, and professional activities.
• Expert evidence — where the harm is to a specialised professional reputation (for example, a medical practitioner, barrister, or financial adviser), expert evidence about the impact of the defamatory allegations within the relevant professional community may be important.

Stage 2 Reforms and Serious Harm

The Stage 2 reforms to the Defamation Act 2005 — which have been enacted in some jurisdictions and are proposed in others as at 2025 — include further procedural provisions relating to the determination of the serious harm question. Some jurisdictions are considering enabling courts to determine the serious harm question as a preliminary issue before the matter proceeds to a full trial, thereby saving costs where the threshold cannot be met. The interaction between the serious harm threshold and the new public interest defence (s 29A) is also an area of continuing development.

Frequently Asked Questions — Serious Harm