Competition Merger control
The UK’s merger control regime is set out in Part 3 of the Enterprise Act 2002. This replaced the previous public interest test which applied under the Fair Trading Act 1973, and made provision for decisions to be taken in most cases by an independent competition authority against a competition-based test, with a framework for intervention to be made and decision making to rest with the Secretary of State in cases involving a public interest consideration. As originally enacted, functions of the regulator were divided between the Office of Fair Trading and the Competition Commission; those functions now lie with the CMA.
	Amendments to Part 3 of the Enterprise Act 2002 were made by the Enterprise and Regulatory Reform Act 2013 in order to introduce statutory time limits and information gathering powers for all parts of the merger review process, introduce a time limited period after a Phase 1 decision where merging parties can offer and negotiate undertakings in lieu of a referral for a more in depth investigation, strengthen the voluntary notification regime by giving the CMA the ability to suspend all integration steps in completed and anticipated mergers, clarify the type and range of measures which the CMA may take to prevent pre-emptive action and introduce financial penalties for breach of CMA interim measures. Those amendments came into force on 1 April 2014.
	The turnover and share of supply tests set out in Part 3 were amended by the Enterprise Act 2002 (Turnover Test)(Amendment) Order 2018 (S.I. 2018/593) and the Enterprise Act 2002 (Share of Supply Test)(Amendment) Order 2020 (S.I. 2020/763), the Enterprise Act 2002 (Share of Supply Test) (Amendment) Order 2018 (S.I. 2018/578) and the Enterprise Act 2002 (Share of Supply) (Amendment) Order 2020 (S.I. 2020/748) to create reduced or revised thresholds for businesses active in certain sectors relevant to national security. These amendments were subsequently repealed by the National Security and Investment Act 2021.
	Further amendments were made to Part 3 of the Enterprise Act 2002 by the Competition (Amendment etc.) (EU Exit) Regulations 2019 (S.I. 2019/93) to correct deficiencies arising as a result of the UK’s withdrawal from the European Union and ensure the domestic regime operates on a freestanding basis. These amendments took effect on Implementation Period Completion Day.