How do police and Crown Prosecution Service guidelines determine if online speech becomes a criminal offence?
Executive summary
Police and CPS decisions about when online speech becomes criminal rest on a mix of statutory offences (notably the Malicious Communications Act 1988, Communications Act 2003 and newer Online Safety Act 2023 provisions), prosecutorial tests in the Code for Crown Prosecutors, and guidance from Ofcom and the CPS; the Online Safety Act introduced new criminal offences such as a Section 179 offence for knowingly sending false information to cause “non-trivial psychological or physical harm” [1] [2]. Critics say arrests for communications offences surged — a Times analysis claimed over 12,000 arrests in 2023 (about 30 a day) — while convictions have fallen, raising questions about threshold and proportionality [3] [4].
1. The legal map: which statutes criminalise online messages
UK criminal law contains several overlapping offences that apply to online speech: Section 1 of the Malicious Communications Act 1988 and Section 127 of the Communications Act 2003 criminalise sending “indecent” or “grossly offensive” messages; public order and stirring‑up offences also apply online; and the Online Safety Act 2023 created new criminal offences that came into force in January 2024, including an offence targeting knowingly false communications that cause non‑trivial harm [4] [5] [1] [2].
2. How police decide to arrest: broad statutes and discretionary judgment
Police referrals and arrests are made under these legacy statutes and new offences, but the laws contain terms—“grossly offensive”, “annoyance”, “needless anxiety”, “menacing” and “stirring up”—that require judgment about context and intent; parliamentary debate and reporting show concern that those broad terms allow wide exercise of police discretion, leading to many arrests for online messages [5] [3] [4].
3. How the CPS decides to prosecute: the Code and offence‑specific guidance
The Crown Prosecution Service applies the two‑stage test in the Code for Crown Prosecutors — is there sufficient evidence for a realistic prospect of conviction, and is prosecution in the public interest — together with offence‑specific CPS guidance (for communications offences) and relevant sentencing guidelines; freedom of expression and peaceful protest are explicit factors the CPS must consider [6].
4. The Online Safety Act changed both platform duties and individual liability
Ofcom and government materials show the Online Safety Act imposed duties on platforms and introduced criminal offences that raise the bar for platform compliance and, in some cases, individual criminal liability; Section 179 criminalises knowingly sending false information intended to cause non‑trivial psychological or physical harm to an audience, a distinct and higher‑penalty offence than older “needless anxiety” provisions [1] [2].
5. Data and dispute: many arrests, fewer convictions — what that signals
A Times analysis (cited by parliamentary libraries) found over 12,000 arrests in 2023 for offensive online communications in data gathered by FOI requests across many forces, while Ministry of Justice conviction figures have declined — a pattern that civil liberties groups say shows chilling effects and potential overreach, though centrally held government arrest data by specific offence are not published [3] [4].
6. Legal thresholds and guidance intended to protect speech — and the tensions
Parliamentary and professional guidance stresses that speech must be more than merely “offensive, shocking or disturbing” to be criminal and that ordinary banter, humour or unpopular opinion should not be prosecuted; nevertheless, critics and some MPs and peers argue that public order and communications offences remain too broad and can be applied inconsistently [7] [5].
7. Competing views: safety advocates vs. free‑speech campaigners
Government and Ofcom frame the legal regime as balancing protection from real harms (including harms to children and harms from disinformation) with free expression; rights groups and free‑speech advocates counter that criminalising false or offensive communications risks empowering state actors to police truth and dissent — an argument voiced by peers and civil liberties organisations in parliamentary debate and commentary [1] [2] [5].
8. What is unsettled or not covered in current reporting
Available sources document the statutes, CPS tests, Ofcom duties, arrest figures cited in press analysis and debates about breadth, but they do not provide a comprehensive, centrally published breakdown of arrests by specific offence across all police forces, nor do they settle how often CPS guidance prevents prosecution after arrest — those gaps are noted in parliamentary library work and press reports [4] [3].
9. Practical takeaway for a person posting online
The law treats intent and context as decisive: sending content that is intended to be false and to cause non‑trivial harm can now be a serious offence under the Online Safety Act; sending material that is menacing, grossly offensive or designed to stir up hatred can trigger public order and communications offences; prosecutors must apply the Code and consider free expression, but police arrest decisions can precede CPS charging and are influenced by statutory breadth [2] [6] [5].
Limitations: this analysis relies on parliamentary briefing, government explainer and press‑cited FOI data summarized in parliamentary sources; it does not draw on unpublished police charging decisions or a full dataset of convictions [4] [1].