# UK competition law overview

> **Key takeaway:** CA 1998 Ch I (agreements) & Ch II (abuse). Enterprise Act mergers + cartel offence. CMA enforcement; CAT private actions. Post-Brexit independent UK regime. Check current digital markets rules.

- **Jurisdiction:** England & Wales
- **Practice area:** Commercial
- **Last reviewed:** 2026-08-04
- **Interactive page:** https://kttclegal.info/library/notes/Commercial/competition-law-uk-overview
- **Keywords:** competition law, CMA, Chapter I, Chapter II, cartel, merger control, abuse of dominance, Competition Act 1998

## What is this about?

UK competition law prohibits anti-competitive agreements and abuse of dominance, and controls mergers, under the Competition Act 1998 and Enterprise Act 2002, enforced primarily by the Competition and Markets Authority (CMA). Post-Brexit the UK regime operates independently of the EU, though analysis often remains conceptually similar.

## What is the core rule?

Chapter I CA 1998 prohibits agreements that prevent, restrict or distort competition and may affect trade within the UK (aligned with former Art 101 concepts). Chapter II prohibits abuse of a dominant position (former Art 102 analogue). Hardcore cartels (price-fixing, market-sharing, bid-rigging) attract the severest civil and possible criminal cartel offence exposure (Enterprise Act). Mergers meeting share-of-supply or turnover tests may be investigated and remedied or prohibited. Private damages actions and follow-on claims sit in the Competition Appeal Tribunal and courts.

## What are the elements or test?

1. Agreement/concerted practice or unilateral conduct?
2. Chapter I restriction by object or effect? Exemptions?
3. Dominance and abuse for Chapter II?
4. Merger jurisdictional thresholds met?
5. Leniency/settlement or private damages strategy?

## Which authorities matter?

- **Competition Act 1998, Chapters I and II** — Core prohibitions on anti-competitive agreements and abuse of dominance.
- **Enterprise Act 2002 (mergers; cartel offence)** — Merger control and criminal cartel offence framework.
- **CMA guidance (agreements, abuse, mergers, leniency)** — Primary practical enforcement standards.

## How does this apply in practice?

Sector regulators may have concurrent powers. Vertical agreements and digital markets attract evolving guidance (including DMU/SMS regime developments — check current law). This is not a full merger filing manual.

## What are common pitfalls?

- Casual information exchange with competitors treated as harmless
- Ignoring UK-specific merger thresholds post-Brexit
- Assuming EU block exemptions automatically apply unchanged
- Dawn-raid unpreparedness

## When would a practitioner use this?

Compliance training, distribution agreements, and merger risk screening.

## Quick reference

CA 1998 Ch I (agreements) & Ch II (abuse). Enterprise Act mergers + cartel offence. CMA enforcement; CAT private actions. Post-Brexit independent UK regime. Check current digital markets rules.

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*Reference material from [KTTC Legal](https://kttclegal.info/), not legal advice. Work product supports instructing solicitors and barristers under their supervision. England & Wales.*