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Public Interest Defence in UK Defamation Law

Section 4 of the Defamation Act 2013 is a journalist’s most powerful legal shield when a true story causes reputational damage but cannot be fully proved. Winning it depends on what you did before publication — not after.

Information, not legal advice. Nothing on this page constitutes legal advice. If you face a defamation claim, consult a qualified media lawyer immediately. Read our full disclaimer.

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What the s.4 defence does

Section 4 of the Defamation Act 2013 creates a statutory defence for publishers who make a defamatory statement on a matter of public interest, even if they cannot prove the statement is true. It replaced the old Reynolds privilege (Reynolds v Times Newspapers [2001] AC 127) which required courts to assess a journalist’s responsible journalism against a non-exhaustive ten-factor checklist.

The s.4 defence is not a licence to publish unverified allegations. It is a protection for journalists who have done their job responsibly — who investigated seriously, sought comment, considered the seriousness of the allegation, and had genuine, reasonable grounds to believe that publication was in the public interest.

The defence fails if a court concludes that the defendant did not actually believe publication was in the public interest, or that no reasonable journalist in their position could have held that belief. Courts also look at whether the defendant took reasonable steps: whether they sought comment from the claimant, and whether their editorial process was consistent with their claimed public interest belief.

The two-part test (s.4(1))

1

The statement was, or formed part of, a statement on a matter of public interest.

This is an objective test. A wide range of topics can qualify: political conduct, public body behaviour, serious corporate wrongdoing, public health, safety, or significant matters of public concern. Celebrity gossip or private conduct with no public dimension usually will not.

2

The defendant reasonably believed that publishing the statement was in the public interest.

This is primarily a subjective test (did you actually believe it?) with an objective check (was that belief reasonable?). Courts look at what you knew, what you verified, what steps you took, and whether your belief was consistent with your conduct. If you took shortcuts, failed to seek comment, or misread available information, you may not satisfy this limb.

Red flags

  • You cannot articulate a clear public interest that goes beyond reader interest or entertainment value.
  • You have made no contemporaneous record of your public interest reasoning before publication.
  • You have not sought comment from the claimant or a person who can speak on their behalf.
  • The allegation is serious (criminal conduct, professional misconduct) and you have not verified it with multiple independent sources.
  • You relied on a single source who had obvious motivation to damage the claimant.
  • You rushed publication under competitive pressure without completing reasonable verification steps.
  • The editorial file contains no record of the verification steps taken or the decision to publish.
  • The story mixes genuine public interest material with private information that adds little to the public interest argument.

Pre-publication public interest checklist

  • Identified and recorded the specific public interest served by publication (e.g. exposing wrongdoing, informing public debate, holding power to account).
  • Considered the seriousness of the allegations and whether the verification steps taken are proportionate.
  • Assessed the reliability and potential bias of each source.
  • Checked whether there was any urgency requiring earlier publication than ideal verification would allow.
  • Sent a right-of-reply request to the claimant (or subject) with reasonable time to respond.
  • Documented the response (or non-response) and how it was considered editorially.
  • Confirmed the editorial decision and the public interest reasoning has been recorded in the editorial file.
  • Considered whether any part of the publication includes material beyond what is needed to serve the public interest.
  • Reviewed relevant IPSO Public Interest exception guidance to ensure editorial conduct is consistent with it.
  • If the story has been updated post-publication, confirmed that the public interest reasoning still supports the updated version.

Document your public interest reasoning now

Use the Public Interest Test Builder to create a structured, timestamped record of your public interest analysis in the format that IPSO and courts expect. Use the Defamation Risk Checklist to assess overall pre-publication defamation exposure.

Common mistakes

  • Confusing public curiosity with public interest. Readers wanting to know something does not make it a matter of public interest in law.
  • Not seeking comment from the claimant before publication. Failure to put allegations to a subject is treated seriously by courts and regulators.
  • Failing to make contemporaneous notes of the public interest reasoning. Notes made after the claim arrives look like retrospective rationalisation.
  • Not distinguishing between what is strictly necessary for the public interest story and what is included for colour or commercial reasons.
  • Assuming that because a similar story appeared elsewhere, the public interest is self-evident and does not need documenting.
  • Applying Reynolds factors mechanically without understanding that s.4 requires a holistic assessment of whether publication was responsible.
  • Conflating the IPSO Public Interest exception with the legal s.4 defence — they operate on related but different bases.

Related guides

Related guides

Primary sources

Frequently asked questions

What replaced the Reynolds privilege defence?
Section 4 of the Defamation Act 2013 replaced the common law Reynolds v Times Newspapers [2001] AC 127 "responsible journalism" defence with a statutory public interest defence. While the old Reynolds factors are no longer a checklist, they continue to inform how courts assess responsible journalism and reasonable belief in practice.
Does the public interest defence require a story to be true?
No. The s.4 defence can succeed even where the publisher cannot prove the truth of the defamatory statement. The defence focuses on (1) the statement being on a matter of public interest and (2) the defendant reasonably believing publication was in the public interest. It is designed to protect responsible journalism about important topics where full proof of truth is not achievable.
When is the reasonable belief assessed?
At the time of publication, not at the time of trial. This makes pre-publication documentation critical. What you recorded, considered, and did before pressing publish is the evidence the court examines. Notes made after a claim arrives carry far less weight — and may look like retrospective rationalisation.
What does Serafin v Malkiewicz tell journalists about the s.4 defence?
Serafin v Malkiewicz [2020] UKSC 23 is a significant Supreme Court judgment on the s.4 defence. It confirmed that the test is primarily subjective — was the defendant's belief in the public interest genuine? — but with an objective check: was that belief reasonable? Mere belief is not enough if no reasonable journalist could have held it.
How does IPSO's Public Interest exception relate to the legal public interest defence?
They are separate but related. IPSO's Public Interest exception under the Editors' Code allows departure from Code clauses (such as privacy and harassment) where there is a genuine public interest. The legal s.4 defence protects against defamation claims. Both require similar documentation: what was the public interest, and was the journalism conducted responsibly? Documents prepared for one purpose will assist the other.
Can a magazine or broadcaster use the s.4 defence, or is it only for newspapers?
The s.4 defence applies to any publisher of a statement on a matter of public interest: national newspapers, local papers, magazines, broadcasters, and online publishers. There is no restriction by format or medium. However, the standard of reasonable belief and responsible conduct will be assessed in context — what is expected of a regional paper may differ from a national broadcaster.