In a preliminary ruling, the ECJ formed the view that online comparison sites are not within the scope of the comparative advertising rules in the Misleading and Comparative Advertising Directive (2006/114/EC). Provided the online comparison site does not provide those products / services itself, then it is not a competitor and is free to rank competing goods / services without being subject to MCAD.
Although not binding in the UK, the UK's comparative advertising rules in the Business Protection from Misleading Marketing Regulations derive from MCAD and the UK courts may have regard to this ruling if asked to consider the same question under the BPRs.
HUK-COBURG Haftpflicht-Unterstutzungs-Kasse Case C-697/23
Article 2(c) of Directive 2006/114/EC of the European Parliament and of the Council of 12 December 2006 concerning misleading and comparative advertising must be interpreted as meaning that the concept of ‘comparative advertising’, referred to in that provision, does not include an online comparison service for goods or services provided by an undertaking which is not a ‘competitor’ within the meaning of that provision, that is to say, which does not itself offer the goods or services which it compares and which therefore operates in a market for separate goods or services. The same applies where that undertaking acts as an intermediary and allows consumers to conclude contracts with undertakings which offer the goods or services concerned, without itself operating in the market for those goods or those services.
https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX%3a62023CJ0697