A business that infringes UK competition law can be fined up to 10% of its worldwide turnover, its directors can be disqualified, and any person who suffered loss can claim damages that exceed the fine. The CMA enforces the two prohibitions in the Competition Act 1998, a firm can appeal to the Competition Appeal Tribunal, and private claims, including opt-out collective actions, are a fast-growing risk. A business under investigation has to manage its exposure, its response to the CMA or a sector regulator, and the damages claims that follow an infringement finding. Where proceedings are brought, regulatory input to the litigation team is provided as disputes co-counsel.

The regulatory framework

A business must not enter into an anti-competitive agreement (section 2, Chapter I) and, if it is dominant, must not abuse that position (section 18, Chapter II). The CMA, and the sector regulators exercising concurrent powers, can open an investigation on reasonable grounds for suspecting a breach, using wide powers to compel documents, enter premises and conduct interviews. The CMA can fine a firm that has infringed up to 10% of its worldwide turnover (section 36(8), with turnover determined under the Competition Act 1998 (Determination of Turnover for Penalties) Order 2000), under a structured penalty methodology, and the court can disqualify a director for up to fifteen years where their conduct as a director makes them unfit to be concerned in the management of a company (Company Directors Disqualification Act 1986, section 9A). Since 1 January 2025 the same exposure follows a breach of a conduct requirement or a pro-competition intervention under the DMCC Act 2024.

A firm can appeal an infringement or penalty decision to the Competition Appeal Tribunal, which reviews Competition Act decisions on the full merits rather than on judicial review principles. The Tribunal reviews the CMA’s decisions under the Digital Markets, Competition and Consumers Act 2024 on judicial review principles, a more deferential standard than the full-merits appeal available under the Competition Act. Penalties are the exception. A firm challenges a penalty for failure to comply with a conduct requirement or a pro-competition order under section 114 of the Enterprise Act 2002, applied by section 89 of the 2024 Act, and on that challenge the Tribunal may quash the penalty or substitute one of a different nature or a lesser amount if it considers it appropriate to do so. An individual who takes part in a hard-core cartel commits a criminal offence carrying up to five years’ imprisonment on conviction on indictment, prosecuted separately from the civil case against the business. Dishonesty ceased to be an element of the offence on 1 April 2014, and remains an element only for agreements made before that date.

Follow-on and collective damages claims

Any person who has suffered loss can bring a follow-on damages claim before the Competition Appeal Tribunal, which is bound by the infringement decision once that decision has become final. Since the Consumer Rights Act 2015, the Tribunal can also hear opt-out collective proceedings, in which a certified representative brings a claim on behalf of an entire class of consumers or businesses without each member having to opt in, save that class members not domiciled in the United Kingdom are included only if they opt in. These collective actions have grown quickly, and several of the largest are against digital platforms. A business found to have infringed can end up paying more in damages than in penalty, and a class action is public throughout.

Exposure	What it involves	Where it is decided
Regulatory penalty	Up to 10% of worldwide turnover for a breach	CMA or a concurrent sector regulator
Director disqualification	Disqualification order of up to fifteen years	Court, on application by the CMA or a specified regulator
Appeal	Full-merits challenge to an infringement or penalty	Competition Appeal Tribunal
Follow-on and collective claims	Damages, including opt-out class actions	Competition Appeal Tribunal

Why competition enforcement matters for your business

A CMA investigation consumes management time and requires careful handling of compelled evidence. The CMA can then fine the business against its worldwide turnover, the court can disqualify a director, and any person who suffered loss can claim damages for years afterwards. In a regulated sector, Ofcom, the FCA or the Payment Systems Regulator can investigate instead of, or alongside, the CMA under the concurrency arrangements. A compliance programme that prevents the infringement costs less than any of this, and a business that assesses its exposure in the first weeks of an investigation keeps more options open. Where proceedings are brought or defended, regulatory input runs alongside the team conducting the litigation.

How we work

Bratby Law can be instructed as direct legal advisors on a specific question, as specialist co-counsel alongside a competition or corporate team, and as fractional general counsel on a retained basis. Rob Bratby currently holds four fractional General Counsel appointments, at The One Touch Switching Company, TelXL, Core Communication and the UK Payments Initiative. A one-year secondment to Oftel adds first-hand experience of how a regulator builds and runs a case. Where an investigation involves personal data, the data protection analysis runs alongside it.

Frequently asked questions about competition enforcement

What penalties can the CMA impose?

For a breach of the Competition Act 1998, up to 10% of the undertaking’s worldwide turnover, set by a structured penalty methodology. Directors can face a competition disqualification order of up to fifteen years, and individual participation in a hard-core cartel is a separate criminal offence. Penalties for breach of the digital markets regime are set under the DMCC Act 2024.

Can a CMA decision be appealed?

Yes. A firm can appeal an infringement or penalty decision under the Competition Act 1998 to the Competition Appeal Tribunal, which reviews it on the full merits. The Tribunal reviews decisions under the digital markets regime on judicial review principles, which gives the CMA more latitude. Penalties under that regime are the exception: a firm challenges them under section 114 of the Enterprise Act 2002, applied by section 89 of the DMCC Act 2024, and the Tribunal may quash a penalty or substitute a lesser one.

What is an opt-out collective action?

It is a class action before the Competition Appeal Tribunal in which a certified representative claims damages on behalf of an entire class, so class members are included unless they opt out, save that class members not domiciled in the United Kingdom are included only if they opt in. Introduced by the Consumer Rights Act 2015, these actions have grown rapidly and several of the largest target digital platforms.

Could a sector regulator investigate instead of the CMA?

Yes. In regulated sectors, Ofcom, the FCA, the Payment Systems Regulator and others hold concurrent Competition Act powers and may take a case instead of, or in coordination with, the CMA. The regulators decide which of them acts under the concurrency arrangements, and the choice affects how the investigation is run.

What is leniency and how does it work?

The first participant in a cartel to report it to the CMA and cooperate fully can secure immunity from financial penalties. Later applicants can obtain a reduction. Leniency is governed by the CMA’s leniency guidance rather than set out in detail in statute, and an individual covered by a successful application can also be protected from prosecution for the cartel offence and from disqualification. Because immunity generally goes only to the first to come forward, the decision whether and when to apply is time-critical and needs early specialist advice.

Does an infringement finding automatically mean I owe damages?

Not automatically. Once an infringement decision has become final, any person who suffered loss can bring a follow-on damages claim before the Competition Appeal Tribunal, which is bound by it, so the case turns on causation and the amount of loss rather than on liability. A claim can be brought individually or as part of an opt-out collective action, so a business can still be paying damages years after it has paid the penalty.

Related digital regulation pages

The other digital regulation pages on this site:

Digital Regulation
SMS Designation and Conduct Requirements
Pro-Competition Interventions
Concurrent Competition Powers
Market Investigations and Studies
Merger Control in Digital Markets
EU Digital Markets Act Compliance

Also see

These cases also raise questions in Telecoms Regulation, Payments Regulation and Data Protection. For commentary on current developments, see our Insights.