The UK has no single national firewall. Websites are blocked through four separate channels:
- High Court injunctions that order the major ISPs to block piracy, counterfeit and illegal sports-streaming sites.
- The Internet Watch Foundation (IWF) list, a voluntary blocklist of child sexual abuse material.
- ISP “family” filters, which are optional for customers and block whole categories such as adult content.
- The Online Safety Act 2023, which now lets Ofcom seek court orders that make ISPs, app stores, payment providers and advertisers cut off non-compliant services.
All four mainly work at the network or DNS level, which is why a VPN usually bypasses them. The exception is the Act’s age checks, which take place on the platform itself.
UK website-blocking mechanisms
| Mechanism | Legal basis | Who decides | What gets blocked | Scale or evidence | Source |
|---|---|---|---|---|---|
| Copyright injunctions | Copyright, Designs and Patents Act 1988, s.97A (added 2003) | High Court | Piracy sites, illegal streams | 48 orders tracked, Feb 2012-Dec 2021 | legislation.gov.uk; Open Rights Group |
| Trade mark injunctions | Courts’ equitable jurisdiction | High Court | Counterfeit-goods sites | Rights-holders must pay ISPs’ implementation costs (2018) | UK Supreme Court, 2018 |
| IWF URL list | Voluntary industry scheme | IWF analysts | Child sexual abuse imagery | 260,699 unique URLs (2025), updated twice daily | IWF |
| ISP family filters | Voluntary ISP practice | ISPs and filter vendors | Categories such as adult content | 10.42% of the top 100,000 sites blocked by default settings | Open Rights Group |
| Online Safety Act business disruption | Online Safety Act 2023, ss.144-147 | Courts, on Ofcom’s application | Services that breach the Act | Fines up to £18M or 10% of global revenue; blocking as a last resort | legislation.gov.uk; GOV.UK |
Court-ordered blocks: copyright, sport and counterfeits
Section 97A of the Copyright, Designs and Patents Act lets the High Court grant an injunction against a service provider that has actual knowledge of someone using its service to infringe copyright. It was inserted on October 31, 2003 (legislation.gov.uk). Rights-holders have used it to make the largest ISPs block torrent sites, streaming portals and, in later orders, illegal live-sports streams.
The Open Rights Group (ORG) tracks these orders. Its list covers 48 orders between February 2012 and December 2021, obtained by music and film industry bodies, the Premier League and UEFA, and trade mark owners such as Cartier and Nintendo (Open Rights Group).
Courts have also blocked counterfeit-goods sites under trade mark law. In Cartier v BT (2018), the Supreme Court held unanimously that ISPs acting as innocent intermediaries are ordinarily entitled to be reimbursed by the rights-holders for the reasonable costs of implementing a blocking order. The ISPs still had to pay the litigation costs in that case, because they had resisted it as a test case (UK Supreme Court, 2018).
The IWF list of child sexual abuse material
The Internet Watch Foundation keeps a list of web pages confirmed to host child sexual abuse imagery. Analysts assess every URL manually, and the list is updated twice a day. In 2025 it contained 260,699 unique URLs. Use of the list is voluntary: ISPs, search engines, filtering companies and hosts license it as IWF members and usually show a “splash page” when they block a URL (IWF). This is the least controversial form of UK blocking, because the content is illegal everywhere and each entry is checked by a person.
ISP family filters and overblocking
The large consumer ISPs offer network-level parental filters that block whole categories of sites, but the filters are not always accurate. ORG’s Blocked project has tested more than 72 million sites and found 808,865 blocked by at least one filter. On default settings, 10.42% of the 100,000 most popular sites were blocked. User reports have led to 2,312 wrongful blocks being removed (Open Rights Group). ORG says the filters often block harmless sites by mistake, including sites aimed at children. These are cumulative project figures rather than a snapshot of one date.
Ofcom’s blocking powers under the Online Safety Act
The Online Safety Act received Royal Assent on October 26, 2023. Ofcom began enforcing duties on illegal content on March 17, 2025, and the child-safety duties, including robust age checks for pornography, followed in late July 2025 (GOV.UK, 2025).
For services that don’t comply, the Act sets out business disruption measures that courts can order on Ofcom’s application:
- Service restriction orders (s.144) can require ancillary services, such as payment processors, advertising networks and search engines, to withdraw their services or stop displaying the non-compliant service (legislation.gov.uk).
- Access restriction orders (s.146) can require providers of an “access facility,” such as internet access services and app stores, to take steps that impede UK users’ access to the service. The steps must be limited, as far as possible, to UK users (legislation.gov.uk).
- Interim versions (ss.145 and 147) allow temporary orders while a case is pending.
Fines can reach £18 million or 10% of qualifying worldwide revenue, whichever is higher (GOV.UK, 2025). In October 2025 Ofcom fined 4chan £20,000 plus £100 a day for non-compliance, and reporting at the time noted that this could escalate to an order requiring UK ISPs to block the site (The Record, 2025). We could not confirm from primary sources whether any access restriction order had been granted at the time of publication.
What VPNs change and what they don’t
Using a VPN is legal in the UK, and the government’s explainer of the Act sets out no rules on VPN use (GOV.UK, 2025).
- Court-ordered and filter blocks are applied by ISPs at the DNS or IP level. A VPN routes traffic around the ISP’s resolver and filters, so these blocks generally stop working, although circumventing a block does not make infringing content legal.
- The content on the IWF list is illegal to access whatever tool you use.
- Online Safety Act age checks happen on the platform, not at the ISP. A VPN with a non-UK exit may change which country’s rules a service applies, but platforms decide how to treat VPN traffic, and the duty to protect children stays with them.
- Future access restriction orders would most likely work at the ISP or app-store level, like copyright orders. That makes them easy to route around for adults who use a VPN.
What this means for you
- If a site you rely on is blocked by your ISP filter, check it on ORG’s Blocked tool and ask your ISP to reclassify it. You can also check the filter settings in your ISP account.
- A court-order notice means the block comes from a High Court injunction obtained by a rights-holder, usually over copyright or trade marks, and not from a general government ruling on the site.
- Parents should know that network filters both overblock and underblock. Device-level controls and conversations about online safety remain important.
- Businesses running user-to-user or search services in the UK face Online Safety Act duties enforced by Ofcom, and in the worst case a court order cutting off their payments, advertising or ISP access.
Methodology and limitations
Sources are primary legislation (legislation.gov.uk), the government’s Online Safety Act explainer, the UK Supreme Court’s press summary in Cartier v BT, the IWF’s published list statistics, ORG’s Blocked project data, and reporting by The Record for Ofcom enforcement. Ofcom’s own website could not be accessed by our tools during research, so enforcement details come from government and press sources, and figures we could not verify, such as VPN download spikes after July 2025 and later Ofcom fines, are left out. ORG’s figures are cumulative and undated, and its court-order list may lag behind new orders. ISP filter performance varies by provider and changes over time.