There are currently a number of means by which the UK government can intervene in transactions that raise national security concerns. Technically these are not limited to foreign investments; they can also apply to purely domestic transactions.
UK Merger control – public interest intervention
The UK merger control regime, contained in the Enterprise Act 2002 (EA02), applies to acquisitions of businesses (whether by share or asset purchases) and the formation of joint ventures, exceeding specified size thresholds. The EA02 gives the Competition and Markets Authority (CMA) power to review a transaction on competition grounds, but the regime also provides for government (Secretary of State) intervention in qualifying transactions on the basis of public interest concerns, such as national security, media plurality and the stability of the financial system.
The Secretary of State may also intervene in transactions that do not meet the UK merger control thresholds. Such "special public interest" cases are rare, being limited to certain mergers in the media sector and mergers in the defence sector involving a relevant government contractor or subcontractor with confidential defence-related information or other material.
Where the government intervenes on public interest or special public interest grounds, by issuing a public interest or special public interest intervention notice, the CMA investigates and reports to the relevant Secretary of State on the public interest implications of the deal. The Secretary of State is the ultimate decision maker (taking further advice as necessary from relevant government departments and officials) on whether the transaction is expected to operate against the public interest, and on the appropriate remedies to address the adverse effects.
EU merger control – intervention to protect legitimate interests
The UK remains bound by the EU merger control regime during the Brexit transition period. Under these rules a Member State can intervene in mergers subject to competition review by the European Commission and take appropriate measures to protect its legitimate interests, which include public security. In these instances the UK issues an EU intervention notice and conducts the review under the EA02; it may impose remedies to address any adverse effects even where the transaction is cleared by the European Commission on competition grounds.
Recent interventions
In November 2019 the Business Secretary issued an EU intervention notice in relation to the proposed acquisition of UK defence company Cobham by the US private equity firm Advent International. While the European Commission cleared the transaction on competition grounds, the UK Business Secretary accepted undertakings, in late December, to mitigate the national security concerns that were identified. Advent undertook to continue to protect sensitive government information, to honour existing contracts and to give prior notice to the Ministry of Defence and the Home Office of any plans to dispose of all or part of Cobham's business.
Just as the Cobham deal was cleared, the Business Secretary issued a (UK) public interest intervention notice in the acquisition of Mettis Aerospace, a supplier of commercial and military aerospace parts, by Aerospace, a Chinese fund, a deal that falls under the UK merger control rules. The CMA delivered its report on the national security aspects of the deal to the Business Secretary on 13 February; at time of writing the report has not been published.