Patent enforcement proceedings

Lawsuits and courts

What legal or administrative proceedings are available for enforcing patent rights against an infringer? Are there specialised courts in which a patent infringement lawsuit can or must be brought?

Patent rights in the United Kingdom are generally enforced against an infringer by bringing a lawsuit in an appropriate court.

In England and Wales (the jurisdiction of the United Kingdom in which most patents lawsuits are brought) both the Patents Court (part of the High Court) and the IP Enterprise Court hear claims for patent infringement. The IP Enterprise Court provides a streamlined and more cost-effective forum to hear lower-value and less complex IP claims than the Patents Court.

Claims exceeding £500,000 or those requiring complex evidence are normally heard in the Patents Court. If either party in a Patents Court or IP Enterprise Court case believes that the other court is a more appropriate forum, it can apply for the dispute to be transferred (although the case will be transferred only if it is appropriate in the circumstances).

Trial format and timing

What is the format of a patent infringement trial?

The IP Enterprise Court and Patents Court are overseen by specialist IP judges who have a high level of technical and patent expertise.

All evidence-in-chief is filed with the court in written form. Any witness may be cross examined.

Experts play a significant role in Patents Court proceedings. The parties will normally appoint one or two independent experts each, who will provide written evidence to the court and be made available for cross-examination at trial. Often, most of the evidence in a patent trial is in the form of expert opinions. The role of expert evidence in IP Enterprise Court proceedings is more limited in scope and confined to key issues determined in advance by the court.

All issues in dispute are decided by the judge alone.

The trial of a single patent typically takes around five days.

Proof requirements

What are the burdens of proof for establishing infringement, invalidity and unenforceability of a patent?

The burden of proof rests on the person pursuing the relevant cause of action, namely infringement must be proven by the patent owner and invalidity must be proven by the party seeking to revoke. The standard applied is the ‘balance of probabilities’.

Standing to sue

Who may sue for patent infringement? Under what conditions can an accused infringer bring a lawsuit to obtain a judicial ruling or declaration on the accusation?

The patent owner or an exclusive licensee can sue for infringement.

Any party may bring a lawsuit for a declaration that a particular act does not constitute infringement of a patent, if that party has first written to the patent owner seeking an acknowledgment to that effect and the patent owner has not given the acknowledgment sought.

Any party aggrieved by the making of unjustified threats to bring patent infringement proceedings may bring a lawsuit against the person making the threats.

Inducement, and contributory and multiple party infringement

To what extent can someone be liable for inducing or contributing to patent infringement? Can multiple parties be jointly liable for infringement if each practises only some of the elements of a patent claim, but together they practise all the elements?

Parties can be sued as ‘joint tortfeasors’ where they are acting together as part of a ‘common design’, in which case all parties involved will be jointly and severally liable for the infringement. It is thus not necessary for one party to practise all of the elements of a patent claim. A party not directly involved in an infringement can be liable as a joint tortfeasor where it has induced the direct infringer to breach the patent.

A party who provides means relating to an essential element of the invention, for putting the invention into effect, knowing, or in circumstances where it would be obvious to a reasonable person, that those means are suitable for putting, and are intended to put, the invention into effect, is also liable for patent infringement (unless the relevant means are a staple commercial product).

Joinder of multiple defendants

Can multiple parties be joined as defendants in the same lawsuit? If so, what are the requirements? Must all of the defendants be accused of infringing all of the same patents?

Multiple defendants can be joined in the same lawsuit. There are no strict rules governing this, but the court is likely to separate lawsuits where the joinder is inconvenient. It would be unusual to sue different defendants on different patents (unless there was a relationship between the defendants or the patents involved that made it convenient to do so).

Where a lawsuit is brought against multiple defendants in the IP Enterprise Court, the damages limit of £500,000 applies to the whole lawsuit.

Infringement by foreign activities

To what extent can activities that take place outside the jurisdiction support a charge of patent infringement?

In general, infringement of a UK patent must take place within the UK. However, it may be possible to bring a lawsuit against a party for activities that took place outside the jurisdiction as part of a claim of joint tortfeasorship, for example where the person outside the jurisdiction induced a person within the jurisdiction to infringe a patent.

Infringement by equivalents

To what extent can ‘equivalents’ of the claimed subject matter be shown to infringe?

Under article 2 of the Protocol on the Interpretation of Article 69 of the European Patent Convention ‘due account shall be taken of any element which is equivalent to an element specified in the claims’.

For a number of years, the UK courts adopted a ‘purposive’ approach to claim construction, under which the relevant question was what a person skilled in the art would have understood the patent owner to have used the language of the claim to mean. Under the purposive approach, there was no justification for extending or going beyond the definition of the technical matter for which the patent owner sought protection in the claims. However, in the landmark ruling of Actavis v Eli Lilly ([2017] UKSC 48), the Supreme Court rejected this approach and in effect introduced a doctrine of equivalents into UK law for the first time (in particular, finding that a variant that falls outside the claims as a matter of normal interpretation may nonetheless infringe where it varies from the invention in a way which is immaterial).

Discovery of evidence

What mechanisms are available for obtaining evidence from an opponent, from third parties or from outside the country for proving infringement, damages or invalidity?

Parties to English litigation can be ordered to give disclosure (called ‘discovery’ in other common law jurisdictions). The English courts take an increasingly limited approach to disclosure. The Patents Court is part of a current ‘disclosure pilot’ that is aimed at ensuring that disclosure is directed to the real issues in dispute and is not wider than is reasonable and proportionate.

At the infringement and validity stage, the court is usually reluctant to make wide disclosure orders, and disclosure is limited to:

  • the alleged infringer being ordered to produce a written description of its product or process instead of being required to disclose documents; and
  • disclosure of documents relevant to validity by the patent owner, but this is limited to documents created in the period two years before and after the claimed priority date (though even this is increasingly rarely ordered).


If the patent owner succeeds on validity and infringement the court will conduct a damages inquiry during which the defendant will typically be required to disclose relevant financial documents to allow a calculation of the damages due (or the profit made).

Litigation timetable

What is the typical timetable for a patent infringement lawsuit in the trial and appellate courts?

The Patents Court seeks to bring cases to trial quickly – where possible, within 12 months of the claim being issued. Expedition is possible where the court considers it warranted.

The Court of Appeal aims to hear cases within 12 months and may expedite a hearing in appropriate circumstances.

Litigation costs

What is the typical range of costs of a patent infringement lawsuit before trial, during trial and for an appeal? Are contingency fees permitted?

A litigant before the Patents Court should expect to pay at least £500,000 and often considerably more where the issues are more complex. Single patent actions involving issues of infringement and revocation typically exceed £1 million in legal fees. If successful, a significant proportion of these fees can be recovered from the other side. However, if unsuccessful, the litigant will likely be ordered to compensate the other party for a significant proportion of its legal fees. Litigants before the IP Enterprise Court should expect to pay considerably less and costs awards are normally capped at £50,000.

Costs on appeal are typically lower than at first instance although they may be in the range of £300,000 to £500,000.

Contingency fee arrangements are permitted.

Court appeals

What avenues of appeal are available following an adverse decision in a patent infringement lawsuit? Is new evidence allowed at the appellate stage?

Appeals can be made against IP Enterprise Court and Patents Court decisions on points of law. Permission to appeal must be sought from the first-instance judge or from the court to which the appeal is addressed (for IP Enterprise Court appeals, either the Patents Court or the Court of Appeal; and for Patents Court appeals, the Court of Appeal). For cases of public importance, a further appeal may be brought to the Supreme Court. Such appeals are not common.

New evidence is not typically allowed on appeal.

Competition considerations

To what extent can enforcement of a patent expose the patent owner to liability for a competition violation, unfair competition, or a business-related tort?

Patent owners are subject to the usual competition law prohibitions on entry into anticompetitive agreements and abuse of a dominant market position. In particular, where a patent owner settles a dispute with an alleged infringer care must be taken to ensure that any settlement agreement does not breach the parties’ competition law obligations.

A person subject to unjustified threats of the bringing of a patent infringement lawsuit may sue the person making the threats, including for compensation for any damage caused by the threats.

Alternative dispute resolution

To what extent are alternative dispute resolution techniques available to resolve patent disputes?

Parties are generally free (and indeed encouraged) to seek alternative means of dispute resolution, such as mediation or arbitration. In the United Kingdom, there is legislation formalising the procedure and enforceability of arbitration proceedings. However, alternative dispute resolution may not be suitable where substantive issues of patent law are likely to arise.

Law stated date

Correct on

Give the date on which the information above is accurate.

29 April 2020.