Defamation and the Online Safety Act 2023: What Has Changed?

The Online Safety Act 2023 (OSA) is the most significant piece of UK internet regulation in a generation. While it does not directly amend defamation law, it creates major new duties for online platforms that intersect with and supplement existing defamation remedies — and every claimant and potential defendant in a defamation dispute needs to understand how it changes the landscape.

What the Online Safety Act Does

The OSA received Royal Assent in October 2023 and is being implemented in phases by Ofcom, the UK communications regulator. Its core mechanism is a regime of safety duties imposed on "user-to-user" services (platforms where users share content with other users) and search services, requiring them to:

• Assess and mitigate illegal content risk — all in-scope services must assess the risk of illegal content on their platforms and take proportionate action to prevent it.
• Protect users from harmful content — larger platforms have additional duties to protect users from content that is harmful to adults, and to protect children from a broad range of harmful material.
• Provide transparency — platforms must publish transparency reports explaining how they deal with harmful content and complaints.
• Maintain effective complaints systems — platforms must have accessible, effective processes for users to report content and challenge moderation decisions.

The "False Communications" Offence

One of the OSA's most significant innovations for defamation claimants is the creation of a new criminal offence under s.179 for sending a false communication. The offence is committed when a person:

• sends or posts a message containing information they know to be false
• with the intention of causing non-trivial psychological or physical harm to the recipient (or to a likely audience)

This is not simply defamation under another name — the offence requires subjective intention to cause harm, which is a higher bar than civil defamation. However, in cases where a defendant has been making a campaign of false statements with clear intent to cause harm, a police report under the OSA offence can run alongside a civil defamation claim and give additional leverage.

How the OSA Interacts with Defamation Remedies

The OSA does not replace or modify defamation law — civil defamation claims remain governed by the Defamation Act 2013. However, the OSA affects how platforms handle complaints, which matters enormously to defamation claimants:

• Faster content removal — platforms with effective OSA-compliant complaints systems should respond more quickly to reports of defamatory content. In practice, platforms are upgrading their moderation infrastructure to comply with Ofcom's codes of practice.
• Improved transparency — transparency reports make it easier to understand platforms' policies for dealing with defamatory and harmful content, and to challenge inadequate responses.
• Regulator as enforcement lever — where a platform fails to comply with its OSA duties, Ofcom can investigate, impose fines (up to 10% of global annual turnover for the largest platforms), and ultimately apply to block services in the UK. This regulatory leverage puts significant pressure on platforms to handle complaints properly.
• [Serious harm](/glossary#serious-harm) evidence — platforms' own transparency data about content reach and engagement may become evidence relevant to the serious harm threshold in defamation proceedings.

Platform Categorisation Under the OSA

The OSA divides platforms into categories based on their size and the nature of their services:

• Category 1 services (the largest platforms, designated by Ofcom) — face the most stringent duties, including duties to protect adults from harmful content and to assess and mitigate "priority harmful content."
• Category 2A and 2B services — face lighter-touch duties but must still comply with core illegal content and transparency obligations.
• Smaller platforms — still have duties in relation to illegal content and child safety, but with reduced compliance burdens.

What Has Not Changed

The OSA does not:

• Modify the elements of a civil defamation claim — the serious harm test, available defences, and remedies remain as under the Defamation Act 2013
• Create a new civil right of action against platforms for hosting defamatory content — platforms retain their intermediary defences under existing law
• Replace the need for a solicitor to pursue content removal — a formal legal letter remains more effective than a platform complaint for serious cases
• Affect the one-year limitation period for defamation claims

Related reading: How to remove defamatory content from the internet | The Defamation Act 2013 explained | Who is responsible for defamatory social media posts?