In the final part of this series, which explores the law on preliminary injunctions (PIs) across Europe, we examine the approach taken in the UK.
Applying for a preliminary injunction
In the UK, the courts have the power to grant a preliminary injunction (PI) at any time (Civil Procedure Rules (CPR) 25.1, 25.2) and therefore there is no time limit within which a PI application must be brought. However, if there is any unexplained or unreasonable delay in making the application, the applicant is unlikely to be successful (Blinkx UK Ltd v Blinkbox Entertainment Ltd [2010] EWHC 1624 (Ch)). As such, a PI application should be made as soon as possible after the applicant becomes aware of the defendant's potentially infringing activities.
It is possible to make an application for a PI without giving notice to the defendant. However, the court will only grant a PI without hearing the defendant (an ex parte PI) if there are good reasons for not giving notice (CPR 25.3(2)). For example, if the applicant believes that the defendant would make efforts to evade an injunction, or where time is of the essence and a defendant cannot reasonably be notified at the time. Evidence in support of an application made without notice must state the reasons why notice has not been given (CPR 25.3(3)). In patent cases, ex parte injunctions are uncommon.
Usually, the court will only grant a PI if the applicant provides an undertaking to compensate the defendant in damages if it is later found that the PI was wrongly granted and the defendant suffered loss as a result. This is known as a cross-undertaking in damages. The court may also require the applicant to show that it has the means to meet any liability under the cross-undertaking. In rare cases, the applicant may be required to provide a security deposit.
Third parties may seek a similar cross-undertaking if the PI is likely to affect them. For example, the National Health Service (NHS) may seek such an undertaking in cases where a PI prevents a generic pharmaceutical company from entering the market, as this means it will likely have to pay more for the relevant product.
Evidence required
An application for a PI must be supported by evidence (CPR 25.3(1)) which may be in the form of a witness statement, a statement of case, or the application (CPR 25.7). The applicant must demonstrate that the following criteria has been met:
- that there is a serious issue to be tried
- that damages would not be an adequate remedy for the applicant in lieu of a PI, and that damages (on a cross-undertaking) would be an adequate remedy for the defendant
- that the balance of convenience lies in favour of granting a PI.
(American Cyanamid Co v Ethicon Ltd [1975] AC 396).
Factors that the court takes into consideration
When considering whether there is a serious issue to be tried, the court needs only to be satisfied that the claim is not frivolous or vexatious. In relation to patent infringement, the applicant must prove that there is at least an arguable case of infringement. However, this is a low threshold. The court will not usually consider points of validity.
In relation to the adequacy of damages, in patent cases it is often the case that damages will be an adequate remedy for the applicant if it is successful at trial because a final injunction will restore the applicant's monopoly and it can recover damages for lost profits due to lost sales and/or price depression as a result of infringing acts in the intervening period (Astrazeneca AB v Glenmark Pharmaceuticals Europe Ltd [2025] EWCA Civ 480). However, this may not be the case in a situation where a generic pharmaceutical company has launched a product at risk of patent infringement. This is because entry into the market by one generic company is often followed by the entry of others, resulting in a downward price spiral and potentially recategorisation of the product in the drug tariff (which affects the reimbursement price). The ability of the patentee to restore its previous price if successful at trial may be constrained by NHS resistance to price rises. It is usually the case that damages will not be an adequate remedy for the defendant either, because it will have no record of selling the relevant product to enable lost sales to be quantified.
Regarding the balance of convenience, the court will consider all the relevant factors in deciding what is least likely to cause irremediable prejudice to one party or the other (Astrazeneca AB v Glenmark Pharmaceuticals Europe Ltd [2025] EWCA Civ 480). The court will also consider special factors such as the public interest and the effect of the injunction on non-parties. Where these factors appear to be evenly balanced, the court is likely to preserve the status quo, eg which companies are on the market (Neurim Pharmaceuticals (1991) Ltd v Generics (UK) Ltd) [2022] EWCA Civ 370). In the case of a generic company launching a product at risk, the court will consider that the generic company could have 'cleared the path' for its launch by bringing proceedings for revocation of the patent sufficiently far in advance (SmithKline Beech plc v Apotex Europe Ltd [2003] EWCA Civ 132).
Obtaining PIs
It usually takes around one to two months to obtain a court ruling on a PI application. However, in cases of genuine urgency, courts can grant PIs within a matter of days.
PIs are rarely granted in patent actions, as in most cases the court will determine that damages would be an adequate remedy for the applicant. The court may instead order an expedited trial. The most common situation in which PIs are granted is when a generic pharmaceutical company enters the market, for the reasons outlined above. Where these factors appear to be evenly balanced, the court is likely to preserve the status quo—for example, by determining which companies remain on the market (Neurim Pharmaceuticals (1991) Ltd v Generics UK Ltd (t/a Mylan) [2020] EWCA Civ 793).
In relation to standard essential patents, the court will likely find that the patentee's losses, ie the loss of FRAND royalties under the patent, are quantifiable and therefore damages are adequate (IPCom v Xiaomi [2019] EWHC 3074 (Pat)).
Enforcement
A PI will become effective as soon as the court issues its order.
A defendant who deliberately breaches a PI order will be in contempt of court and may be imprisoned, fined, or have their assets seized. It is normal to include a penal notice in the PI which warns the defendant that failure to obey its terms could result in court proceedings (known as committal proceedings). Committal proceedings are the only remedy available for breach of an injunction. A contempt of court does not, of itself, allow the applicant to seek damages for loss arising from a breach of the PI.
Appeal
Either the applicant, the defendant or a third party who is directly affected may appeal the grant or refusal of a PI.
The party must first obtain permission to appeal to the Court of Appeal, which the court can give at first instance (the High Court) or the Court of Appeal itself. An appeal to the Court of Appeal can take one to three months. Appeals can also be made on an expedited basis for cases of genuine urgency, which can be heard within a matter of days or weeks. Following the Court of Appeal's decision, a further appeal may be made to the Supreme Court. Again, permission to appeal is required. An appeal to the Supreme Court can take between six and 18 months. However, as with the Court of Appeal, this may be expedited.
The court will make an order regarding whether a granted PI will be continued pending resolution of the appeal.
If a granted PI is later found to be unjustified, the applicant will be required to compensate the defendant for loss suffered because of the PI under the cross-undertaking in damages discussed above. The approach is compensatory and not punitive, and the court will estimate what may have happened if the PI had not been granted, for example, whether the generic company would have entered the market with full force, the degree of success it would have achieved and the profits it would have made (Les Laboratoires Servier v Apotex Inc [2008] EWC 2347, AstraZeneca v KrKa [2015] EWCA Civ 484).
Damages can only be awarded for losses caused by the order itself, not losses caused by the existence of the patent and the underlying litigation (Dr Reddy's Laboratories (UK Ltd) v Warner-Lambert Company LLC [2021] EWHC 2182 (Ch).
