Competition damages claims are generally pursued on the basis of the tort of breach of statutory duty.  The statutory basis for a claim depends on the nature of the alleged infringement and the period in which the cause of action arose:

• The Chapter I prohibition, contained in the Competition Act 1998 (“CA98”), prohibits agreements between undertakings or concerted practices whose object or effect is to prevent, restrict, or distort competition within the UK (section 2(1)).
• The Chapter II CA98 prohibition concerns conduct by an undertaking that amounts to an abuse of a dominant position in a market, where such conduct may affect trade within the UK (section 18(1)).
• Articles 101 and 102 of the Treaty on the Functioning of the European Union (“TFEU”) concern conduct analogous to that caught by the Chapter I and II prohibitions, respectively.

Since the expiry of the UK’s post-EU withdrawal transition period on 31 December 2020, Articles 101 and 102 TFEU no longer have direct application in the UK.  Notwithstanding this, a claimant retains the right to pursue a claim grounded in an infringement of Article 101 or 102 TFEU that took place prior to that date, provided the claim could have been brought before 31 December 2020.

Where a claimant relies on a pre-existing finding of infringement by a relevant competition authority, such as the Competition and Markets Authority (the “CMA”), the claim is classified as a ‘follow-on’ action. In such proceedings, the claimant is not required to establish the underlying infringement (i.e. liability), as that is taken to have been proven by the competition authority’s decision.

The European Commission retains competence under the UK/EU Withdrawal Agreement and UK domestic legislation to decide cases in which it had formally opened its investigation procedure before 31 December 2020.  Where the Commission makes an infringement decision in such a case after 31 December 2020, a claimant may rely on that decision as binding proof of the infringement it establishes.

Where the claimant does not rely on any prior competition authority decision and instead alleges an infringement of competition law, the proceedings are referred to as ‘standalone’.  In standalone proceedings, the claimant must establish the defendant’s liability for the alleged infringement.

Claims that combine follow-on and standalone elements are commonly described as ‘hybrid’ actions.

Competition damages claims may be commenced either in the Competition Appeal Tribunal (“CAT”), which has UK-wide jurisdiction, or in the civil courts (see Q6 for further detail).  Proceedings are started with a claim form.

Starting proceedings in the CAT

The claim form must set out prescribed details, including:

• details of the parties;
• whether the claim is based on an infringement decision and, if so, confirmation of whether that decision has “become final“ (see Q10 for further detail);
• a concise statement of the relevant facts, identifying any relevant findings within an infringement decision, cross-referring to the relevant sections of that decision where applicable;
• a concise statement of any legal arguments upon which the claimant relies; and
• the relief claimed, which in the context of a damages action must include an estimate of the sum sought together with an explanation of how that figure has been calculated (which may be set out in an annex).

(Rule 30 of the CAT Rules).

Starting proceedings in the civil courts

Claims in the civil courts must comply with the applicable court rules and procedural requirements. Where proceedings are brought in the High Court of Justice for England and Wales, which is the most frequently used civil court forum for competition damages actions, the governing rules are the Civil Procedure Rules (“CPR”).

The CPR requires only that the claim form include:

• the identities of the parties;
• an outline of the claim; and
• a statement of value.

However, the claimant must provide further detail in respect of its case through the ‘particulars of claim’, which must ordinarily be filed within 14 days of the claim form being served.

Service of the claim form

As a general rule, the claim form must be served on the defendant. Where the defendant is located outside the jurisdiction, the claimant may need to apply for the court’s permission to serve the defendant abroad.

The standard of pleading

A party’s statement of case must enable the opposing party to understand the case that is being advanced against it and identify the principal facts underpinning each main element of the cause of action.  These pleading standards apply to all competition litigation claims, regardless of the forum.

There are three remedies available to claimants in competition claims:

• An award of damages and interest (see Q4 and Q19 for further detail).
• Injunctive relief (or, in Scotland, interdicts) requiring or restraining particular
• Declaratory relief, which is a binding statement by the court that determines the rights of the parties.

The vast majority of competition claims seek only damages.

Measure of damages

The general principle is that tort damages are compensatory rather than punitive in nature: their purpose is to place the claimant in the position it would have been in, but for the competition law infringement.

The loss claimed is typically formulated as the difference between the amounts actually paid by the claimant and those which would have been paid in a competitive market but for the breach of competition law (the ‘counterfactual’ scenario), commonly referred to as the ‘overcharge’.  Claims arising from abuse of dominance tend to involve other heads of loss, including a claim for loss of profits.

A claimant may also seek damages to compensate it for the cost of financing its principal losses attributable to the infringement, such as interest payments under a loan agreement that were inflated as a result of the claimant having to finance overcharges (please refer to Q19 for further detail).

There are two exceptions to the general principle (that damages are compensatory in nature) in competition damages claims:

• The CAT has the power to award aggregated damages on behalf of a class in collective proceedings. It can do so without the need to assess the individual loss sustained by each class member (please refer to Q12 for further detail).
• Secondly, the civil courts and the CAT have jurisdiction, in narrowly defined circumstances, to award exemplary damages.

Joint and several liability

Where an infringement (or alleged infringement) involves multiple parties, as a general rule, each participant is jointly and severally liable for the entirety of the harm caused by the infringement (the participants being ‘joint tortfeasors’).  A claimant may accordingly choose to pursue a single participant for the full extent of its loss.  A claimant is not required to bring proceedings against every participant.

In the case of infringements established by a competition authority decision, the general rule is subject to an exception where a participant in the infringement has been granted leniency by the competition authority (please refer to Q17 for further detail).

The allocation of liability as between joint tortfeasors is a distinct issue (please refer to Q20 for further detail).

The applicable limitation period is determined by reference to a number of factors, including the forum in which the claim is brought.

The answer below does not address the position for claims brought in the CAT prior to the Consumer Rights Act 2015 coming into force on 1 October 2015.

High Court (England and Wales; Northern Ireland)

In the High Court of Justice for England and Wales and the High Court of Justice for Northern Ireland, claims are subject to a six-year limitation period. The rules governing the operation of this limitation period differ depending on whether the loss or damage was sustained before or on/after 9 March 2017 (as discussed further below).

Court of Session (Scotland)

In the Court of Session (Outer House), a five-year prescriptive period applies.  As with the High Court, the rules governing the running of this period vary depending on whether the loss or damage was sustained before or on/after 9 March 2017 (see below).

CAT

For proceedings commenced in the CAT after 1 October 2015, the applicable limitation rules turn on when the claim is taken to have ‘arisen’ for limitation purposes.

Where the claim arose before 1 October 2015, transitional provisions apply.  These include a special two-year limitation period which runs from the later of (i) the date on which the relevant infringement decision became final (having exhausted any appeals or appeal deadlines) and (ii) the date on which the cause of action accrued. This two-year limitation period applies to both follow-on and standalone competition claims (with limb (i) being irrelevant in standalone claims).

Where the claim arose after 1 October 2015, a six-year limitation period applies. Again, the rules governing the operation of this period differ according to whether the loss or damage was sustained before or on/after 9 March 2017 (see below).

Loss or damage suffered before or on/after 9 March 2017

As described above, the rules governing the limitation period vary depending on whether the relevant loss or damage was incurred wholly before, or on/after, 9 March 2017 – the date on which Directive 2014/104/EU (the ‘Damages Directive’) was transposed into UK law.

For loss or damage sustained before 9 March 2017:

• The standard six-year limitation period (or five-year prescriptive period in Scotland) runs from the date on which the cause of action accrued.
• However, where the defendant has deliberately concealed from the claimant any fact that is essential to completing the cause of action, time does not begin to run until the claimant discovers the concealment or could have done so with reasonable diligence.

For loss or damage sustained on or after 9 March 2017:

• The limitation period begins on the later of (a) the date on which the infringement ceases, and (b) the date on which the claimant first knows or could reasonably be expected to know: (i) of the infringer’s conduct, (ii) that such conduct constitutes an infringement of competition law, (iii) that the claimant has suffered loss arising from the infringement, and (iv) the identity of the infringer.
• In addition, the limitation period is suspended for the duration of any investigation by a relevant competition authority. If the authority makes a finding of infringement, the investigation period is treated as ending one year after the resulting infringement decision becomes final.
• The initiation of collective proceedings may have the effect of suspending the limitation period in respect of any new proceedings brought in relation to the same or overlapping claims.

Where damages are alleged to have been sustained over a period that straddles 9 March 2017, the infringement is treated for limitation purposes as having taken place before that date.

With the exception of competition collective actions, which must be commenced in the CAT, competition damages claims may be brought either before the CAT or in the civil courts.

Cases before the CAT are heard by a three-member Tribunal. The panel ordinarily comprises the President of the CAT or one of its Chairs, together with two Ordinary Members. The Chairs are supplemented by designated judges of the Court of Session, the High Court of England and Wales, or the High Court of Northern Ireland.  Ordinary Members bring expertise drawn from fields including economics, law, business, technology, and accountancy.

In the UK, civil court proceedings are most commonly issued in the High Court of Justice for England and Wales, which has jurisdiction in England and Wales.  Such claims are generally assigned to either the Competition List or the Commercial Court and are determined by a High Court Judge.

The High Court may transfer proceedings to the CAT, either on application by the parties or of its own initiative.  The Court of Appeal has indicated that claims concerning infringement decisions or alleged breaches of domestic or EU competition law should in normal circumstances be transferred to the CAT. Where the proceedings also raise non-competition issues, it is possible to transfer only the competition issues.

International instruments

For proceedings initiated on or before 31 December 2020, Regulation (EU) 1215/2012 (the “Recast Brussels Regulation”) governs the jurisdiction of an English court over EU-domiciled defendants. In a similar manner, the Lugano Convention governs questions of jurisdiction between the EU and Norway, Iceland, and Switzerland and applies to proceedings commenced in the UK on or before 31 December 2020.

For proceedings commenced after 31 December 2020, neither the Recast Brussels Regulation nor the Lugano Convention apply.  Issues relating to jurisdiction are instead resolved in accordance with the common law of England and Wales (or the law of Scotland or Northern Ireland, where relevant).

Domestic law

Private competition damages claims, whether standalone or follow-on, may be pursued either in the civil courts (for example, the High Court of Justice for England and Wales) or in CAT.  Only the CAT has jurisdiction to hear collective proceedings.

Whether the civil courts have jurisdiction depends on the applicable domestic law (of England and Wales, Scotland, or Northern Ireland).

Taking the position in England and Wales for example, a court will have jurisdiction (without the need for the claimant to seek the court’s permission) if the defendant can properly be served with proceedings because it:

I. has a place of service in England and Wales (for example, a registered office) at which it carries on its activities; or

II. has nominated English solicitors or an agent authorised to accept service on its behalf.

In the case of proceedings before the CAT, the relevant test is whether the defendant can be served anywhere in the UK (rather than only England and Wales).

Where the defendant cannot be served within the jurisdiction, a claimant may apply to the CAT or the civil court (as applicable) for permission to serve proceedings abroad, as necessary.

To determine what law will apply to a competition damages claim, one must consider the relevant time periods for the claim.  The analysis also varies depending on the relevant domestic law (England and Wales, Scotland, or Northern Ireland).  By way of illustration, the following answer addresses the position under the law of England and Wales.

Infringement prior to 1 May 1996

For an infringement which occurred before 1 May 1996, the English common law choice of law rules, including the principle of “double actionability“, apply.  According to this principle, a tort committed abroad is generally only actionable in England if the tort: (i) would have been actionable if it had been committed in England and Wales, and (ii) it is actionable in the jurisdiction where it was actually committed.  However, in practice, this general principle is applied flexibly, and the courts can require its modification or disapplication where it is in the interests of justice to do so.  Furthermore, the choice of law rules permit a specific issue between the parties to be governed by the law of the country with the most significant relationship to both the events in question and the parties.

Infringement between 1 May 1996 and 10 January 2009

For infringements falling within the period from 1 May 1996 to 10 January 2009, the applicable law is ascertained under the Private International Law (Miscellaneous Provisions) Act 1995 (the “1995 Act”). The general rule, set out in section 11, is that the applicable law will be that of the country in which the events constituting the tort took place.  In competition claims, this means the law of the country where the “most significant element or elements“ of the tort occurred, taking into account factors such as where the restriction of competition occurred and where the resulting loss was suffered.  This is determined with regard to the particular facts of the case.

Infringement after 11 January 2009

For the period from 11 January 2009 onwards, Article 6(3) of EC Regulation 864/2007/EC (“Rome II”) applies.  Rome II continued to apply throughout the UK’s post-withdrawal transition period and was subsequently incorporated into UK law as assimilated law.

The default rule under Article 6(3)(a) is that the applicable law is that of the country “where the market is, or is likely to be, affected.”

Where more than one national market is or is likely to be affected, a claimant bringing proceedings in the courts of the defendant’s domicile may alternatively elect under Article 6(3)(b) to apply the law of the court seized, provided the market in that Member State is among those “directly and substantially affected“ by the restriction of competition giving rise to the claim. Under this limb, it is not sufficient for the market merely to be “likely to be“ affected; the effect on that market must be direct and substantial.

Where proceedings are brought against multiple defendants, the claimant may only rely on the law of the court seized if the restriction of competition underpinning the claim against each defendant “directly and substantially affects“ the market in the Member State of that court.

The applicable standard of proof is the “balance of probabilities”.  The claimant must satisfy the court or the CAT (adducing supporting evidence as necessary) that the matter that they seek to establish (such as an infringement of competition law in standalone proceedings) is more probable than not to have occurred.

Where the claimant has established on the balance of probabilities that they have suffered some loss, the claimant is entitled to be compensated, and the CAT or civil courts will do their best to quantify the compensation on the available evidence.  Therefore, the balance of probabilities standard does not apply to the measure of loss where some loss has been established (see Q4 for further detail).

Domestic competition authorities

Competition infringement decisions of the CMA (and of sectoral regulators with competition powers) are binding on both the CAT and the civil courts.  A claimant in a ‘follow-on’ action may therefore rely on such a decision to establish liability, without the need independently to prove the infringement.  As a result, follow-on proceedings typically focus on questions of causation and the quantification of loss.

Foreign competition authorities

The CAT and the civil courts are additionally bound by competition infringement decisions made by the European Commission:

• on or prior to 31 December 2020 (the end of the post-withdrawal transition period for the UK); or
• after 31 December 2020, where the Commission retains ‘continuing competence’ by virtue of having opened its investigation procedure before that date.

In both scenarios, the Commission’s decision may serve as the foundation for a follow-on claim in the UK.

Beyond these categories, decisions of other foreign competition authorities (and decisions of domestic regulators that are not competition infringement decisions, such as regulatory decisions) do not automatically bind the CAT or the civil courts.  However, a claimant may seek to persuade the CAT or civil courts to treat such decisions, when made against the defendant in the proceedings, as admissible evidence.

The extent to which an infringement decision is binding

It is common for the CAT or the civil courts to determine, at a preliminary stage of proceedings, precisely which aspects of the relevant infringement decision are binding.  The applicable legal principles depend on the nature and source of the decision in question.

In the case of a European Commission infringement decision, it is generally only the ‘operative part’ of the decision that binds the court or the CAT, together with those recitals which furnish the ‘essential basis’ or ‘necessary support’ for the operative provisions. The remaining content of the decision is not binding.

Where the infringement decision is made by the CMA or the sectoral regulators, findings are binding on the civil courts and the CAT:

I. under section 58A CA98, to the extent that they are integral to, or directly relevant to, a clearly identifiable and definitive finding of infringement; and/or

II. under section 58 of the CA98, to the extent that they constitute clearly identifiable findings of fact to a specified effect, unless the civil courts or the CAT direct otherwise.

Where the infringement decision is a ‘settlement decision’, meaning the addressees have admitted to anti-competitive conduct, and the claimant relies on that decision, the defendant may be prevented from resiling from those admissions (irrespective of the decision’s binding effect) under the ‘abuse of process’ doctrine recognised in English law.

Relevance of appeals

An infringement decision is binding only once it has become ‘final’. This requires that: (i) the time for bringing any appeal against the decision has expired without an appeal being lodged; and (ii) any appeal that has been brought (together with any further appeal) has been determined or otherwise concluded, and the period for any further appeal has elapsed without one having been filed (please refer to Q10 for additional detail).

The civil courts and the CAT are precluded from delivering judgments that might conflict with decisions contemplated by the CMA (or the European Commission in respect of investigations opened before the end of the transition period).

Where public enforcement proceedings are pending and private damages actions seeking to follow on from those proceedings have been commenced, the trial of the private claims cannot take place until the public enforcement proceedings have been concluded.

A number of mechanisms exist in the UK for aggregating competition damages claims. The most prominent of these is the collective proceedings regime in the CAT.

Collective proceedings regime

A proposed class representative starts the proceedings on behalf of a class (or classes) of persons who have allegedly suffered loss as a result of an established or alleged competition law infringement.

Before a collective action can proceed, it must be certified through the grant of a ‘collective proceedings order’ (“CPO”).  In considering whether to make a CPO, the CAT must satisfy itself that the proposed class representative is a just and reasonable person to act in that capacity and that the claims are suitable for inclusion in collective proceedings.  The CAT will also determine whether the proceedings should be conducted on an opt-in or opt-out basis.

A ‘carriage dispute’ may arise where two or more applicants seek to bring overlapping collective proceedings.  In such circumstances, the CAT will decide which proposed class representative is best suited to act on behalf of the class.

Other case management approaches

It is common for a significant number of individual (non-collective) damages claims to be filed in connection with the same underlying infringement.  To mitigate the risk of inconsistent outcomes and the costs and burden of multiple trials addressing the common issues, the CAT has developed procedures for managing related proceedings in a coordinated manner.

The CAT has adopted an ‘Umbrella Proceedings’ practice direction that sets out one possible approach to directing that issues arising in one set of proceedings be resolved together with identical or substantially similar issues in other proceedings, referred to as ‘Ubiquitous Matters’.  The CAT made an Umbrella Proceedings order in relation to the Multilateral Interchange Fees litigation.  It also adopted a similar approach (albeit not pursuant to the practice direction) in relation to the second wave of the Trucks litigation.

There are also examples of the CAT case managing related claims together (including collective and non-collective proceedings concerning the same infringement) and directing a single trial of issues common to multiple proceedings.  One scenario where this is likely to arise is where claims have been brought by claimants at different levels of the supply chain.  For example, where claims have been brought on behalf of both (i) a business that alleges that it suffered an overcharge and (ii) consumers who purchased products or services from that business and allege that the overcharge was passed on to them, then it is possible that the CAT will decide to have a single trial at least in respect of the common issue of pass-on (please refer to Q13 for additional detail as regards the pass-on defence).

Assignment of claims

The assignment of competition claims is constrained by English law rules on champerty and maintenance.  As a consequence, the consolidation of claims through assignment to special purpose vehicles established for that purpose is not a feature of the competition damages landscape in England.

The pass-on defence can apply if the defendant successfully argues that a claimant’s loss has been reduced, in whole or in part, because the claimant has either (i) negotiated lower costs from its own suppliers or (ii) increased the prices charged ‘downstream’ to its own customers, thereby mitigating the economic impact of the overcharge.

The burden is on the defendant to prove that the loss has been passed on (rather than the claimant needing to show it has not).  The applicable legal test for causation is that the defendant must prove that there was a direct and proximate causative link between (i) the overcharge and (ii) the negotiation of lower costs or increase in prices.  It is not enough for the defendant to point to the fact that the overcharge (as a cost to the claimant) was an input into the claimant’s usual planning and budgetary process and that the relevant prices increased.

The pass-on defence is routinely raised in competition damages proceedings and gives rise to considerable legal and evidential complexity, particularly in cases involving multiple claimants sitting at different levels of the supply chain.

In addition to serving as a ‘shield’ for defendants, pass-on may operate as a ‘sword’ for indirect purchaser claimants.  An indirect purchaser may argue that the overcharge was transmitted down the supply chain and caused it harm by increasing the prices it paid.  In such circumstances, the burden of demonstrating that pass-on occurred is on the indirect purchaser (as claimant).

Where the claim is governed by the Damages Directive and is brought by an indirect purchaser, there is a rebuttable presumption that the overcharge was passed on to that indirect purchaser.

Whether the pass-on defence is confined in law to competition damages claims remains an open question.  In practice, this is the only area of law where the defence has been regularly advanced and considered by the courts.

Expert evidence is only admissible in competition proceedings if it has been permitted by the court (or CAT) and complies with the applicable procedural rules.

In the High Court of Justice for England and Wales, expert evidence is covered by Part 35 of the CPR, which provides that expert evidence shall be restricted to that which is reasonably required to resolve the proceedings. Part 35 also imposes a duty on experts to help the court on matters within their expertise, and this duty to the court overrides any obligation to those instructing them.

For cases in the CAT, Rule 21 of the CAT Rules empowers the Tribunal to give directions as to whether expert evidence may be adduced, the issues on which such evidence is required, and the way in which it can be presented to the Tribunal. Paragraph 7.67 of the CAT Guide to Proceedings provides that an expert is subject to an overriding obligation to the CAT to assist on the matters within his or her expertise (which mirrors the position in the High Court).

On 2 December 2025, the CAT published Practice Direction 3/2025 on Expert Evidence.  The Practice Direction sets out certain general principles that are applicable to the evidence of any expert in the CAT, as well as certain specific principles applicable to economic evidence.  This includes, for example, an expectation that experts engage constructively with one another and with the Tribunal, and that they “acknowledge and respond in a fair-minded manner to evidence and views that challenge their positions, changing their minds if appropriate, particularly where the facts change or new evidence emerges”.  Specific areas addressed by the Practice Direction include instructions to experts, involvement of experts in disclosure, requirements for expert reports (including that they must be “concise and confined to the issues in dispute” and are likely to be subject to page limits), and procedures for experts giving evidence at trial.

The CAT frequently requires the parties to prepare a list of issues on which expert evidence will be adduced, and in which fields, at an early stage in the proceedings.

Each party’s expert(s) will ordinarily prepare written reports for exchange with the opposing party’s expert(s) and will subsequently have the opportunity to respond to those reports.  It is standard practice for the experts to be directed to produce at least one joint statement identifying the principal areas of agreement and disagreement for the benefit of the court.

Experts are typically cross-examined at trial, sometimes in addition to giving concurrent evidence alongside other experts in the same discipline in a process known as ‘hot-tubbing’.  This is a procedure in which the parties and the CAT put questions to the experts simultaneously.

Civil courts

Proceedings in the civil courts are ordinarily determined by a single judge, who serves as the sole decision-maker.  Juries are not used in competition cases in the UK.

The rules of evidence are set out in the applicable court rules and procedures.  In the High Court of Justice for England and Wales, the relevant provisions are found in Part 32 of the CPR and the common law.

In the case of factual witnesses, the parties exchange written witness statements and documentary evidence in advance of trial, in accordance with Parts 32 to 35 of the CPR.  Witnesses called to give oral evidence at trial will typically be cross-examined by the opposing party’s counsel.

The same general procedure applies to expert witnesses (please refer to Q14 above for further detail).

CAT

Proceedings before the CAT are typically heard by a panel of three members, consisting of the President or a Chairman and two Ordinary Members (please refer to Q6 above for further details).  The panel collectively acts as the decision-maker at trial.

The rules relating to evidence in the CAT are set out in the CAT Rules and the CAT’s Guide to Proceedings.

The procedure for factual witness evidence in the CAT broadly mirrors that of the High Court of Justice for England and Wales, as described above.  The CAT retains a broad discretion to restrict the scope of cross-examination as it considers appropriate.

The treatment of expert evidence in the CAT also follows a similar pattern to that in the High Court, although the CAT has demonstrated a greater willingness to question experts directly, including through ‘hot-tubbing’ (please refer to Q14 above for further details).

The time taken to bring a competition damages claim to trial is influenced by a number of variables, including the complexity of the proceedings, the number of parties, whether claims have been consolidated with other proceedings, the volume of factual and expert evidence, and whether appeals against interlocutory decisions have caused delay.

Private damages actions

Relatively few competition damages claims have progressed to a full trial in either the CAT or the civil courts, with the majority settling at an advanced stage.  Among those that have gone to trial, the period from commencement to full trial has been around four to five years, both in the High Court of Justice for England and Wales and in the CAT.

Collective proceedings

At the time of writing, only two collective actions have been determined following a full trial.  The average period from commencement of proceedings to full trial for these two actions was just over 4 years.  Added to this is the time taken for any appeals to run their course.

Appeals

Judgments of the High Court of Justice for England and Wales, the Court of Session (Outer House), and the High Court of Justice for Northern Ireland may be appealed to the Court of Appeal of England and Wales, the Court of Session (Inner House), and the Court of Appeal of Northern Ireland, respectively.

Parties can appeal decisions of the CAT to the Court of Appeal, the Court of Session (Inner House), or the Court of Appeal of Northern Ireland, depending on whether the proceedings are treated as having taken place in England, Scotland, or Northern Ireland.

Permission to appeal is ordinarily sought in the first instance from the court or tribunal that produced the decision under challenge (for example, the High Court or the CAT). If that application is refused, permission may be sought directly from the appeal court.

Judgements of the Court of Appeal of England and Wales, the Court of Session (Inner House), and the Court of Appeal of Northern Ireland can be appealed to the Supreme Court of the United Kingdom. Appeals to the Supreme Court are rare and permission is granted only where the appeal raises an ‘arguable point of law of general public importance which ought to be considered by the Supreme Court at that time’.

In claims for loss or damage wholly suffered on or after 9 March 2017 (the date on which the relevant provisions in the Damages Directive, as transposed into UK law, came into force), leniency recipients in respect of a cartel infringement benefit from certain protections in the context of damages litigation.

Specifically, applicants that have been granted full immunity are generally liable only for the loss caused to their own direct and indirect purchasers.  As a result, they will not be jointly and severally liable for the entire loss flowing from the infringement, save where the claimant is unable to secure full compensation from an immunity applicant’s ‘co-infringers’. In addition, an immunity applicant’s obligation to contribute to the liability of co-infringers is capped at a level reflecting its relative share of responsibility for the damage caused (see Q20 for further detail).

Assessment of loss and favoured methodologies

The objective of damages in competition claims is to restore the claimant (or, in collective proceedings, the class) to the position it would have been in but for the infringement.  Compensatory damages may encompass recovery of excess payments or costs, lost profits, and/or financing costs.

Quantification frequently involves extensive factual evidence and highly technical economic analysis. Where the quantification is difficult (as it typically is), the civil courts and the CAT will apply the so-called “broad axe” principle to estimate loss, doing the best it can on the available evidence.

The type of expert analysis employed varies according to the nature, value, and scope of the claim and the number of parties.  Economic evidence is almost always adduced.  More recently, the courts and the CAT have also admitted evidence from other disciplines, including forensic accountancy and behavioural economics.

There is a limited exception to the compensatory principle in individual (non-collective) competition claims, under which the CAT and civil courts can, in narrowly defined circumstances, award exemplary damages.  This is designed to be used to punish particularly egregious conduct and to deter future infringements.

Umbrella effects

‘Umbrella effects’ refer to the broader market impact of an infringement beyond the direct conduct of the infringers themselves. By way of illustration, where cartel participants increase their prices, competitive dynamics may lead non-participants to raise their prices as well, thereby causing loss to purchasers who have transacted with parties that were not participants to the cartel.

It is an established principle, derived from EU case law, that claimants may recover damages resulting from umbrella effects from the competition law infringers.

Claims for statutory interest

Claimants can claim simple interest on damages under certain statutory provisions (for example, section 35 of the Senior Courts Act 1981 in respect of claims in the High Court of Justice for England and Wales).  Both the civil courts and the Competition Appeal Tribunal (“CAT”) exercise a wide discretion as to the rate and period of interest to be awarded.  The CAT’s conventional approach for commercial claimants is to award simple interest calculated by reference to the Bank of England base rate (as it varies from time to time) plus a margin of 2%.

Claims for interest as a head of damages

As an alternative, a claimant may seek interest as a distinct head of loss reflecting its actual financing costs.  Claims of this nature typically seek compound interest.  The claimant must plead and prove the financing cost losses in question, including the applicable rate, with recovery being subject to the usual principles of remoteness, failure to mitigate, and other constraints.

Contribution claims

As discussed in the response to Q4, where multiple ‘tortfeasors’ have participated in an infringement (for example, as a cartel), they are usually jointly and severally liable for the losses arising from the infringing conduct.  Accordingly, a claimant is ordinarily entitled to bring its claim against any one of those tortfeasors for the entirety of the loss suffered.

In those circumstances, it is standard practice for the defendant against whom the claim is pursued to seek a ‘contribution’ from co-infringers towards any share of the damages that it is ordered or agrees to pay.

As explained at Q17 above, for proceedings commenced on or after 9 March 2017, a tortfeasor that has obtained immunity from the relevant competition authority benefits from an exception to the general rule.  Such immunity applicants are liable only for the harm caused to their direct and indirect purchasers, unless the claimant cannot obtain full compensation from the remaining co-infringers.

Allocation of liability

The basis on which liability is apportioned between defendants depends on the applicable domestic law (i.e., England and Wales, Scotland, or Northern Ireland).

Under the common law of England and Wales, the level of contribution required from a defendant must be just and equitable, having regard to the extent of that person’s responsibility for the damage in question.

This approach is broadly aligned with the approach specified in the Damages Directive, which stipulates that each defendant’s contribution should be calculated by reference to its proportionate share of responsibility for the loss arising from the infringement.

The Damages Directive additionally provides that a defendant’s joint and several liability in respect of a claim is discharged when that defendant settles its share of the claim.

Settlement

The majority of competition damages claims are resolved before trial through negotiated settlements between the parties.  Only a small fraction of the claims have proceeded to a final hearing.

Settlement is available in collective proceedings as well as in individual actions. Settlements of collective claims before the CAT will, however, typically require the CAT’s approval (please refer to the response to Q22 below).

Strike out and summary judgment/summary decree

A competition damages claim may also be disposed of, in whole or in part, at an early stage through: (i) an application to strike out (in England and Wales/Northern Ireland); or (ii) summary judgment (in England and Wales/Northern Ireland) or summary decree (in Scotland). The following discussion addresses the position under the law and procedural rules of England and Wales.

Strike out

The strike-out powers available to the CAT (under Rule 11 of the CAT Rules) and the High Court of Justice for England and Wales (under CPR rule 3.4) are broadly equivalent.  A claim or defence may be struck out where it: (i) discloses no reasonable grounds for bringing or defending the proceedings; or (ii) constitutes an abuse of the court’s process.  In addition, both the CAT and the High Court may strike out a claim for failure to comply with a procedural rule.  A frequently encountered form of strike-out application in both forums is a challenge on ‘limitation’ grounds, where a defendant argues that some or all of the claim is time-barred.

Summary judgment

A related mechanism for the early disposal of a claim is summary judgment.  Under Rule 43 of the CAT Rules and CPR Part 24, the CAT and the High Court respectively may determine the whole or any part of a claim or a specific issue where a party has no real prospect of success and there is no other compelling reason for the matter to proceed to trial.

Preliminary issue hearing

A further avenue for pre-trial determination is the hearing of a preliminary issue.  The court or the CAT may direct that a discrete question be resolved in advance of trial where doing so has the potential either to dispose of the entire claim or to reduce the issues requiring determination at trial. In deciding whether to order a preliminary issue hearing, the court or CAT will weigh factors including whether it is likely to result in a more cost-effective and efficient route to trial and whether the issue can properly be dealt with at a preliminary stage.

The principal differences between a preliminary issue hearing and a strike-out or summary judgment application are twofold: (i) the court or CAT exercises a discretion as to whether to order a preliminary issue hearing (by contrast, a strike-out or summary judgment application will always be considered by the court/CAT); and (ii) the standard of proof at a preliminary issue hearing is the balance of probabilities, as opposed to the higher threshold applicable to strike-out and summary judgment (as outlined above).

Refusal of CPO application

In the specific context of collective actions, proceedings will not advance to trial if the CAT declines to certify proceedings by making a CPO.

In the case of opt-in proceedings, claims may be settled by agreement between the parties without the need for the involvement of the CAT.

For opt-out collective claims, Rule 94 of the CAT Rules establishes a distinct procedural framework for collective settlement of opt-out claims. This rule requires the approval of the CAT for a collective settlement to become effective and legally binding.

The class representative and the defendant(s) are required to submit a joint application to the CAT seeking approval of the settlement terms.  Approval will be granted only if the proposed terms are considered “just and reasonable” from the perspective of the class members.  In its assessment, the CAT will scrutinise the settlement amount (including costs), the likelihood of a larger sum being awarded if the case proceeds to trial, the anticipated cost and duration of continued proceedings, and any other matters to which the parties may refer in their submissions.

It is also possible for a collective settlement to be reached before a collective proceedings order has been granted.  In that event, the CAT must make a collective settlement order and appoint a collective settlement representative to act on behalf of the claimants in respect of the proposed settlement.

A notable feature of the CAT’s collective settlement framework is that the terms of the settlement can provide that any unclaimed balances of damages revert to the defendant(s) (see Rules 94(9)(g) and 97(7)(g)). This mechanism may serve as an incentive to resolve claims by settlement, as no equivalent provision is available where the CAT awards damages following a trial of collective proceedings.

Disclosure

In the civil courts, the framework for disclosure orders is set out in the relevant court rules and procedures.  In the High Court of Justice for England and Wales, for example, the relevant framework is CPR Part 31 and its ancillary Practice Directions.  Parties are usually required to prepare disclosure reports and electronic documents questionnaires.  However, unlike many other claims in the High Court, competition damages proceedings are not (unless otherwise ordered) subject to Practice Direction 57AD, which provides for disclosure in the Business and Property Courts.

In proceedings brought before the CAT, disclosure is regulated by Rules 60 to 65 of the CAT Rules, the CAT Practice Direction on disclosure, and case law.

The scope and mechanics of disclosure remain actively contested in many competition claims.  Although ‘standard disclosure’ (where a party is required to disclose only the documents on which they rely and the documents which adversely affect their own case, adversely affect another party’s case, or support another party’s case) continues to be available, the CAT and the civil courts (but particularly the CAT) are inclined to adopt category-based disclosure rather than standard disclosure (or standard disclosure is confined to specific issues).

Disclosure may also be sought from third parties, subject to the applicant demonstrating that the documents are likely to support its case or undermine another party’s case, and that disclosure is necessary in the interests of justice or to save costs.

Following the implementation of the Damages Directive, the High Court or the CAT may not make a disclosure order directed at a competition authority in respect of its investigation file unless satisfied that the documents cannot reasonably be obtained from any other source.

Exceptions to disclosure

A party is entitled to withhold documents from inspection on the grounds of legal professional privilege.

In addition, following the transposition of the Damages Directive, a party cannot be compelled to disclose either a settlement submission made to a competition authority that has not been withdrawn or a cartel leniency statement.  A further prohibition applies to the disclosure of a competition authority’s investigation materials while the investigation remains open.

Confidentiality does not, of itself, provide a basis for withholding documents from inspection.  Under the CPR and the CAT Rules, a party receiving disclosed documents is subject to an implied undertaking that the documents will be used only for the purposes of the proceedings in which they are disclosed (the ‘collateral use prohibition’), unless: (i) the document has been referred to in open court; (ii) the High Court or the CAT (as applicable) grants permission for wider use; or (iii) the disclosing party and the document’s owner have provided their consent to collateral use.

In practice, commercially sensitive documents are frequently safeguarded through disclosure into a ‘confidentiality ring’, which limits access to a specified group of individuals who are typically required to execute confidentiality undertakings.  Additional protections may be adopted at hearings, such as requesting the court to sit in private when confidential material is being discussed.

In January 2024, the CAT published a practice direction addressing the management of confidential information in CAT proceedings.  Parties are encouraged to agree a confidentiality protocol in advance of the first case management conference and to provide reasons why a confidentiality ring is necessary in the particular circumstances of their case.

Litigation costs

The general rule is that costs follow the event: the unsuccessful party is ordered to pay the costs of the successful party, including legal fees.

Both the High Court of England and Wales (under CPR rule 44) and the CAT (under Rule 104 of the CAT Rules) have substantial discretion when assessing costs.  Relevant factors include the conduct of the parties before and during the proceedings, the level of fees charged by the parties’ legal advisors, and whether a party succeeded on certain issues but not others.

Limiting costs recovery

Particular costs consequences apply when a party accepts or rejects a settlement offer made in accordance with CPR Part 36 (in the High Court) or Rule 45 of the CAT Rules.  Depending on the circumstances, these consequences may include shifting costs liability and the imposition of additional costs sanctions.

The CAT and the civil courts also have the jurisdiction to impose cost-capping orders.  In practice, however, this power is rarely exercised, with costs budgeting being the more common mechanism (albeit cost budgeting has rarely been ordered in the CAT).

Third-party litigation funding has become a well-established feature of competition damages proceedings in the UK and has been instrumental in driving the rapid expansion of collective actions in recent years.  Although litigation funding is not subject to formal regulation, a number of funders voluntarily adhere to the “Code of Conduct for Litigation Funders”, which was launched in November 2011.

Lawyers in England and Wales are permitted to act under conditional fee arrangements (“CFAs”), whereby the fees payable by the client vary according to the outcome of the proceedings.  Any success fee payable under a CFA cannot be recovered from the opposing party.

‘Damages-based agreements’ (a form of contingency fee arrangement) are also permitted, save in respect of opt-out collective actions.  In late July 2023, the Supreme Court held in R (on the application of PACCAR Inc and others) v Competition Appeal Tribunal and others [2023] UKSC 28 that litigation funding agreements entitling the funder to recover a percentage of any damages awarded constitute damages-based agreements.  Such agreements are unenforceable in opt-out collective actions and, in other contexts, may be unenforceable if they do not comply with the applicable regulatory requirements. This ruling prompted a number of claimants to restructure their funding arrangements.

In June 2025, the Civil Justice Council published a report recommending the government legislate to reverse the PACCAR decision as soon as possible.  While such legislation is yet to be introduced, the UK Government has (on 17 July 2026) launched a consultation on reforms to the collective proceedings regime which includes reversal of PACCAR (please refer to the response to Q28 below for further details).

Parties can expect to incur substantial costs in bringing a claim to trial, with the expense of legal representation, expert evidence, and the litigation process in the UK serving as a potential deterrent to would-be claimants.  The growth of third-party litigation funding has, however, gone some way towards mitigating this hurdle.

Another obstacle is the length of time involved in litigating competition damages claims.  The CAT’s caseload has increased significantly over the last few years, driven by the rise of collective proceedings.  Although both the civil courts and the CAT have adopted innovative case management techniques aimed at improving efficiency, the path from commencement to trial remains a lengthy one.  Case timelines have also been extended by parties appealing interlocutory decisions, including certification decisions in collective proceedings.

In addition, competition damages claims are typically complex and inherently uncertain.  Notwithstanding the rapid development of the case law in this area over the last few years, including some significant trial judgments and appellate decisions on fundamental issues, obtaining a reliable estimate of loss and/or (in standalone proceedings) a robust assessment of liability at an early stage of proceedings remains a considerable challenge.

The most significant developments affecting competition litigation in the next five years are likely to be external to the regime itself.

First, wide-ranging legislative reform is on the horizon.  On 17 July 2026, the UK Government launched a consultation which focuses on three areas, including opt-out collective competition claims.  The proposals include:

• raising the threshold for certifying collective proceedings, including the introduction of a requirement to consider, amongst other things, the likely class take up, a test for the absolute suitability of a claim, and an increased focus on sufficiency of evidence to assess aggregate damages and the weighing of the likely costs of proposed proceedings versus potential benefits;
• reforming litigation funding, including reversing the decision in PACCAR by removing the prohibition on DBAs in opt-out proceedings;
• codifying the requirements for class representatives, including in respect of funding and control of costs, governance of claims and consultative panels, and independence; and
• reforming costs management, including a requirement for post-certification budgets and introducing sanctions for parties that unreasonably drive up litigation costs.

If implemented, these reforms have the potential to reshape collective proceedings.  If the legislative aim is met and the certification stage hurdle is meaningfully raised, then we are likely to see greater scrutiny of proposed proceedings by the CAT and possibly a lower proportion of them being certified (the Tribunal has rarely declined to certify proceedings, and in the handful of cases where it has, it has generally proceeded to certify the proceedings at a later stage).

Secondly, there is the impact of the CMA’s activities exercising its digital markets functions under the Digital Markets, Competition and Consumers Act 2024 (“DMCCA”):

• We are likely to see the first appeals of decisions of the CMA when exercising its new digital markets functions under the DMCCA by undertakings designated as having strategic market status (“SMS”), and possibly private actions brought against SMS-designated undertakings that have been found by the CMA (or are alleged by the claimant) to have breached a conduct requirement (or another type of relevant requirement) imposed by the CMA.
• We are already starting to see claims brought in the CAT that seek to rely on DMCCA decisions designating undertakings as having SMS (or even merely decisions to open investigations into whether an undertaking has SMS) as having evidential value. This is a trend that is likely to increase as the CMA makes greater use of its digital markets functions.
• The CAT and civil courts are going to need to grapple with the role (if any) of CMA decisions made under the DMCCA in competition proceedings, including whether it is fair to defendants to admit such decisions (and the findings of the CMA contained within them) into evidence. This engages many of the same considerations that the CAT has faced when parties have sought to rely on the decision of foreign competition authorities (please refer to the response to Q10 above for further details).