Understanding Patent Infringement In The UK

If you design, make, sell or import innovative products or tech, patent infringement is one of those risks you can’t ignore. A single letter before action can derail a launch - but with the right checks and a plan, you can stay protected and respond confidently.

This guide breaks down patent infringement in the UK in plain English: what it is, how to avoid it, what to do if you’re accused, and how to enforce your own patent without burning cash or goodwill. We’ll also cover simple contracts and policies that reduce risk from day one.

What Is Patent Infringement In The UK?

In simple terms, a UK patent gives its owner the exclusive right (for up to 20 years from filing, subject to renewal fees) to stop others from making, using, selling or importing the patented invention in the UK without permission. Patents are governed mainly by the Patents Act 1977, and examined and granted by the UK Intellectual Property Office (UKIPO).

Infringement is assessed against the patent’s “claims” - those numbered statements at the back of a patent that legally define the invention. If your product or process contains all the features of a claim (or an equivalent), it can infringe even if you didn’t copy it and even if you made improvements.

Common Ways Businesses Infringe (Often Accidentally)

• Manufacturing or importing a product that falls within the scope of a patent claim.
• Using a patented process in production, even if the output looks different.
• Supplying essential parts or “means” for someone else to infringe (secondary infringement).
• Marketing materials that teach customers to use a patented process.

There are some limited exceptions (for example, private non‑commercial use, certain experimental or clinical trial use), but these are narrow and rarely cover commercial activity.

If you’re developing something potentially patentable yourself, consider your filing strategy early so you can secure protection and avoid public disclosures that could harm novelty - our primer on patenting your app explains the basics that apply broadly beyond software.

How To Avoid Infringing Someone Else’s Patent

The good news: with a bit of process, you can materially lower the risk of patent infringement before you launch.

Build Freedom‑To‑Operate (FTO) Checks Into Your Development Cycle

An FTO review assesses whether your product or process is likely to infringe any live patents in your target market (here, the UK). It’s different from a novelty search (which focuses on whether your own invention can be patented).

• Search public databases. Start with UKIPO, EPO’s Espacenet and Google Patents to identify relevant patents in your product space.
• Focus on granted, in‑force patents. Pending applications are useful to watch, but only granted patents can be infringed. Check legal status and expiry.
• Read the claims first. Abstracts and titles can mislead; the claims determine scope.
• Document your analysis. Keep a record of what you checked and why you concluded low risk - it helps with decision‑making and, if needed, showing you acted responsibly.

For products with real commercial stakes, it’s wise to get a legal opinion on FTO (including risks under the “equivalents” approach used by UK courts). A written opinion helps you refine design choices and can reduce risk of being found to have infringed “knowingly.”

Design Around

If you find a relevant patent, you may be able to modify your design or process to avoid at least one essential claim feature. Effective design‑arounds target claim language, not just overall function.

Use NDAs Before You Share

When collaborating with suppliers, manufacturers or potential partners pre‑launch, use a straightforward Non‑Disclosure Agreement so your R&D detail isn’t circulated unnecessarily. It won’t cure infringement, but it reduces leakage and supports later enforcement if needed.

Get Your IP Ownership Clean

Investors and acquirers will ask: do you own your IP? Ensure your employee and contractor arrangements assign IP to your business from day one. If external developers or engineers help build your product, make sure their contracts include clear IP assignment provisions - see our guide to intellectual property and independent contractors and consider using a tailored IP Assignment when you need to transfer rights.

Register What You Can

Patents protect inventions, but you’ll usually have other brand and content assets worth protecting too. Complementary rights make your position stronger (and put competitors on notice). For example, lock in your name and logo with trade mark registration and use copyright licences for third‑party content where needed.

What To Do If You Receive A Patent Infringement Letter

Receiving a “cease and desist” or “letter before action” is stressful - but don’t panic, and don’t reply in the heat of the moment. Here’s a sensible playbook.

1) Preserve And Triaging

• Keep everything. Save the letter, envelopes, screenshots, product versions, supplier communications and dates of first sale or manufacture.
• Check what’s being asserted. Is it a UK patent? Is it granted and in force? What claim numbers are cited? What acts (making, importing, using, selling) are alleged?

2) Pause Risky Activities (If Appropriate)

If the risk appears material, consider a short voluntary pause on the specific activity alleged (for example, a feature toggle) while you assess. A measured pause can reduce exposure and demonstrate reasonableness.

3) Get A Legal Assessment

You’ll want a practical view on three questions: non‑infringement (do your products meet all claim features?), invalidity (are there good novelty or obviousness arguments?) and commercial strategy (negotiate, redesign, licence or fight?). An experienced IP lawyer can help you weigh cost, timing and leverage - start with an IP Lawyer Consult to plot your next steps.

4) Beware “Unjustified Threats” Rules

In the UK, it’s unlawful to make groundless infringement threats against certain parties (notably retailers and customers). The Intellectual Property (Unjustified Threats) Act 2017 sets out who you can contact and how. If you plan to respond robustly or send your own letters, make sure they’re carefully worded - over‑zealous letters can backfire.

5) Consider Commercial Outcomes

Often there’s a business solution: a design‑around, a phased change, or a licence on sensible terms. If a licence makes sense, a formal IP Licence can grant the permissions you need across territories, fields of use and time, with the right warranties and limitations.

Enforcing Your Own Patent: Strategy, Evidence And Costs

If a competitor is free‑riding on your R&D, enforcing your patent is about smart strategy, not just legal strength. Think timing, evidence, costs and the commercial “ask.”

Get Your House In Order

• Confirm your patent status. Is the patent granted, renewed and in force in the UK? Are there divisional patents or related rights that might help?
• Map the claims. Prepare a clear claim chart matching each claim feature to the competitor’s product or process. Screenshots, teardown photos and public documentation help.
• Capture evidence. Buy samples, keep invoices, record web pages (with timestamps) and product manuals. For process claims, look for marketing materials that describe how the process works.
• Sanity‑check validity. Identify any obvious prior art problems that could be raised against you and factor that into strategy.

Pick The Right Forum And Budget

In England and Wales, patent cases are usually brought in the High Court (Patents Court) or in the Intellectual Property Enterprise Court (IPEC). IPEC offers a streamlined procedure with caps on recoverable costs and damages, which can be attractive for SMEs with proportional disputes.

Remedies can include injunctions, damages or an account of profits, orders for delivery up or destruction and publicity orders. Interim injunctions are possible but require strong evidence and urgency. Most disputes settle before trial once both sides have seen the claim chart and assessed risk.

Use Commercial Levers First

A well‑judged letter before action can open the door to a licence, sell‑off periods, design changes or co‑existence. Keep unjustified threats rules in mind: target the manufacturer or importer rather than end retailers or customers, and stick to factual, specific allegations tied to claim language.

Think Holistically About IP

Sometimes patents aren’t your only (or best) lever. Consider complementary tactics: take down requests based on trade mark or copyright issues, contractual steps against distributors, and brand protection through trade marks. If you need to discuss how these pieces fit together, an IP Lawyer Consult can help prioritise the fastest, most cost‑effective path.

Contracts And Policies That Reduce Patent Risk

Good paperwork won’t magically prevent infringement, but it’s a big part of risk management and value creation for your business.

Employment And Contractor IP

• Ensure employment contracts assign inventions and related IP to the company and require disclosure of inventions developed in the course of employment.
• For freelancers and agencies, include express assignment of all IP created - don’t rely on implied rights. Use a tailored IP Assignment where needed.

Confidentiality And Collaboration

• Use NDAs before discussing prototypes, algorithms or manufacturing methods with third parties. A simple Non‑Disclosure Agreement sets the ground rules and deters misuse.
• If you plan to commercialise with a partner, set expectations in writing (ownership of improvements, who files patents, who pays, and what happens if the relationship ends).

Licensing And Monetisation

• If licensing‑in technology, your IP Licence should clearly grant rights to make, use, sell and import in the UK, address sublicensing, indemnities and infringement handling.
• If licensing‑out, consider field‑of‑use limits, minimum royalties and audit rights. Reserve rights you need for your core market.

Filing And Publication Hygiene

• Avoid disclosing your invention publicly before filing (websites, pitch decks, trade shows). Early disclosure can destroy novelty.
• If you need to publish or pitch, time it after filing, or keep the inventive detail out of public materials and use NDAs for deeper conversations.

Complementary Protection

Patents are only one part of your IP. Brand assets, designs and content often carry day‑to‑day value. Build a layered approach with trade marks and correct copyright practices to deter copycats and support enforcement - if you’re unsure where patent ends and other IP begins, our guide on infringing copyright is a helpful companion.

If you’re at the planning stage, our article on patenting your app walks through timing and strategy that equally applies to hardware and other inventions.

Key FAQs About Patent Infringement (Short Answers)

What Defences Are There?

Common defences include non‑infringement (your product doesn’t meet all claim features), patent invalidity (lack of novelty or inventive step), prior use and certain limited statutory exemptions (for example, experimental use). Many disputes settle around a design‑around that avoids a key claim feature.

How Long Do I Have To Sue?

As a general rule, you have six years from the act of infringement to bring a claim in England and Wales. Don’t wait - delay can increase damages issues and limit interim relief options.

Do I Have To Mark My Product With The Patent Number?

Patent marking isn’t mandatory, but marking products with relevant patent numbers (or virtual marking via a webpage) can help with deterrence and damages arguments. Just make sure markings are accurate; false marking can cause issues.

What Will It Cost?

Costs vary widely. Early legal opinions and negotiation are usually a fraction of full litigation. If litigation is necessary, IPEC’s capped‑costs regime can make proportionate enforcement feasible for SMEs, while the Patents Court is suited to higher‑value or more complex matters.

Key Takeaways

• Patent infringement in the UK turns on the patent’s claim language - if your product or process contains all essential features of a claim (or an equivalent), you can infringe even without copying.
• Build freedom‑to‑operate checks into your development process, document your analysis and consider design‑arounds early to minimise risk pre‑launch.
• If you receive an infringement letter, preserve evidence, pause risky features if needed, get a legal assessment and beware unjustified threats rules before sending any response.
• When enforcing your own patent, assemble clear evidence, pick the right forum (IPEC vs Patents Court), and start with commercial options like licences or phased changes where appropriate.
• Tighten your paperwork: assign IP from employees and contractors, use NDAs before sharing, and licence technology with clear scope and responsibilities.
• Layer your protection - combine patents with trade marks and copyright practices to strengthen your overall IP position.

If you’d like tailored help with patent infringement risks, FTO checks, cease and desist letters or licensing, you can reach us on 08081347754 or team@sprintlaw.co.uk for a free, no‑obligations chat.