The Competition Appeal Tribunal (Amendment) Rules 2025

The Secretary of State, having consulted in accordance with section 15(1) of the Enterprise Act 2002¹ , makes these Rules in exercise of the powers conferred by— (a) section 15(1) and (3)(c) of, and Part 2 of Schedule 4 to, that Act; and (b) sections 101(5) and 102(6) of the Digital Markets, Competition and Consumers Act 2024².

Citation, commencement and extent 1. (1) These Rules may be cited as the Competition Appeal Tribunal (Amendment) Rules 2025 and come into force on 1st October 2025. (2) These Rules extend to England and Wales, Scotland and Northern Ireland.

Amendment of the Competition Appeal Tribunal Rules 2015 2. The Competition Appeal Tribunal Rules 2015³ are amended in accordance with these Rules.

Amendment to rule 2 3. In rule 2 (interpretation), in paragraph (1), in the definition of “damages”, after “the 1998 Act” insert “, or section 101 of the 2024 Act (rights to enforce requirements of Part 1)”.

Amendment to rule 3 4. In rule 3 (application of Rules)— (a) in paragraph (b), after “4,” insert “4A,”; (b) for paragraph (d) substitute— (d) Part 4 applies— (i) to claims under section 47A of the 1998 Act; (ii) subject to rule 72B, to claims under section 101 of the 2024 Act; and (iii) subject to rule 74, to collective proceedings; and (c) after substituted paragraph (d) insert— (da) Part 4A applies to claims under section 101 of the 2024 Act;.

Amendment to Part 3 heading 5. In the heading of Part 3, at the start insert “Review and appeal”.

Insertion of Part 4A 6. After rule 72 insert— Part 4A CLAIMS UNDER SECTION 101 OF THE 2024 ACT 72A. Scope and interpretation (1) The rules in this Part apply to claims under section 101 of the 2024 Act (rights to enforce requirements of Part 1). (2) In this Part— “CMA breach decision” has the same meaning as in section 102(5) of the 2024 Act; “digital activity” has the same meaning as in section 118(1) of the 2024 Act; “relevant requirement” has the same meaning as in section 101(4) of the 2024 Act; and “undertaking” has the same meaning as in section 118(1) of the 2024 Act. 72B. General (1) Part 4 of these Rules applies to claims under section 101 of the 2024 Act in accordance with this rule. (2) Any reference in Part 4 to— (a) a claim brought under section 47A of the 1998 Act is to be read as a reference to a claim brought under section 101 of the 2024 Act; (b) proceedings brought under section 47A of the 1998 Act is to be read as a reference to proceedings brought under section 101 of the 2024 Act; and (c) “the application of Chapter I or II of Part 1 of the 1998 Act” is to be read as a reference to “the application of Part 1 of the 2024 Act”. (3) Rule 30 (manner of commencing proceedings) applies to claims under section 101 of the 2024 Act with the following modifications— (a) any reference to an infringement decision is to be read as a reference to a CMA breach decision; and (b) any reference to an infringement decision becoming final within the meaning of section 58A of the 1998 Act is to be read as a reference to a CMA breach decision becoming final within the meaning of section 102(2) of the 2024 Act. (4) Rule 71 (transfer of claims from the Tribunal) is to be read as if “or the county court” were omitted. 72C. CMA notice The CMA shall, within 28 days of receiving a copy of a claim form sent under rule 33(7), notify the parties and the Tribunal in writing— (a) whether it has begun, or has decided to begin, an investigation under Part 1 of the 2024 Act concerning issues the same as, or similar to, those raised in the claim; or (b) whether it has decided against such an investigation. 72D. CMA application for stay (1) This rule applies where the CMA— (a) gives notice under rule 72C that it has begun, or decided to begin, an investigation concerning issues the same as, or similar to, those raised in the claim; or (b) decides at any other time before the proceedings are concluded to begin such an investigation. (2) The CMA shall, within seven days of giving the notice referred to in paragraph (1)(a) or making the decision referred to in paragraph (1)(b)— (a) apply for a stay of the proceedings; or (b) notify the parties and the Tribunal that it does not consider that the proceedings should be stayed, with reasons. (3) An application under paragraph (2)(a) shall— (a) be supported by reasons as to why the CMA considers that the proceedings should be stayed; (b) indicate whether the CMA considers that the application should be determined without a hearing; (c) be served on the parties by the CMA; and (d) be determined by the Tribunal taking into account any observations of the parties, including as to whether the application should be determined without a hearing. 72E. Stay of proceedings (1) In determining whether to stay proceedings by reason of a CMA investigation under Part 1 of the 2024 Act (whether on the application of the CMA or otherwise), the Tribunal shall have regard to all the circumstances including— (a) the undertaking and the digital activity which are the subject of the claim and the investigation; (b) the terms and the purpose of the relevant requirement which is the subject of the claim and the investigation; (c) the conduct which is the subject of the claim and the investigation; (d) the extent to which any factual or legal issues to be considered and determined in the investigation will be relevant to the claim; (e) the stage of the proceedings at which the stay is sought, and its likely duration; and (f) where the CMA decision to investigate was made after it gave notice under rule 72C, any explanation provided by the CMA for the time at which that decision was made. (2) A stay ordered by reason of a CMA investigation shall remain in place for a period of no more than 12 months, unless extended on the application of the CMA in accordance with paragraph (3) or otherwise ordered. (3) An application by the CMA to extend the period of a stay ordered by reason of a CMA investigation shall be supported by evidence addressing the progress of the CMA investigation and the period within which it is expected to be completed. 72F. CMA notice of final breach decision The CMA shall notify the Tribunal and the parties in writing within seven days of a CMA breach decision concerning issues the same as, or similar to, those raised by the claim becoming final within the meaning of section 102(2) of the 2024 Act (treatment of CMA breach decisions etc).

Amendment to rule 104 7. In rule 104 (costs), in paragraph (1), after “the 1998 Act”, insert “or section 101 of the 2024 Act (rights to enforce requirements of Part 1)”.

Explanatory Note (This note is not part of the Rules) These Rules amend the Competition Appeal Tribunal Rules 2015 (S.I. 2015/1648) (“the CAT Rules”) to insert procedural requirements for claims brought in the Competition Appeal Tribunal (“the Tribunal”) under section 101 of the Digital Markets, Competition and Consumers Act 2024 (c. 13) (“the 2024 Act”). A person may bring a claim under section 101 of the 2024 Act where they sustain loss or damage as a result of a breach of a requirement imposed by the Competition and Markets Authority (“the CMA”) under Part 1 of the 2024 Act on an undertaking designated by the CMA as having strategic market status in respect of a digital activity. Rules 3 to 5 make consequential amendments to the CAT Rules in relation to claims under section 101 of the 2024 Act. Rule 6 inserts a new Part 4A into the CAT Rules dealing with claims under section 101 of the 2024 Act. Part 4A includes the following provisions. Rules 72A and 72B make technical provision for the application and interpretation of Part 4A, and for its interaction with other provisions of the CAT Rules. Rule 72C requires that the CMA notify the parties and the Tribunal when it is investigating issues the same as, or similar to, those raised by a claim under section 101 of the 2024 Act. Rule 72D requires that the CMA apply for a stay of proceedings where it is investigating such issues, or notify the parties and the Tribunal that it does not consider that the proceedings should be stayed. Rule 72E makes provision for the Tribunal’s determination of whether to order a stay. Rule 72F requires the CMA to notify the parties and the Tribunal where a CMA breach decision becomes final within the meaning of section 102(2) of the 2024 Act. Rule 7 makes a further consequential amendment to the CAT Rules to refer to claims under section 101 of the 2024 Act. An impact assessment has not been produced for this instrument as no, or no significant, impact on the private, voluntary or public sectors is foreseen. An impact assessment was produced for the 2024 Act and is available from the Department for Business and Trade at Old Admiralty Building, Admiralty Place, London SW1A 2DY.