• In the case of R v Monopolies and Mergers Commission, ex parte South Yorkshire Transport Ltd [1993] 1 WLR 23, it was found that the court refrains from involving themselves with the decision making duties of a public body based on an interpretation of law unless the interpretation made by the public authority.

Facts of the Case

  • D, the MMC, came to the conclusion that the merger of bus companies in the South Yorkshire area would contravene the public interest given that the reference area is ‘a substantial part of the United Kingdom’ under section 64(3) of the Fair Trading Act 1973.
  • C, the bus companies, applied for judicial review of D’s decision.
  • D interpreted the term ‘substantial’ as ‘something real or important as distinct from something merely nominal.’ D argued that the relevant area in this case included important features and characteristics.
  • The Court of Appeal found in favour of C, and D subsequently appealed this decision to the House of Lords.


  • Did D act outside of their powers?
  • Was D’s interpretation of the Act capable of being reviewed, and if so, is it acceptable?

Held by the House of Lords

  • The House of Lords allowed the appeal and found that the Act gave D the appropriate jurisdiction to investigate, and the court also concluded that D’s inference of the Act was seen as rational, therefore there could not be any grounds for judicial review.

Lord Mustill

  • His Lordship emphasised D’s jurisdiction but also recognised the potential for the court to interfere. Had D undertook a radical misconception, the court would have been authorised to intervene in the interpretation of the Act.
  • “Thus far, therefore, I accept the respondents’ submission that if the commission proceeded when examining its jurisdiction on the basis that it was enough for the reference area to be more than trifling this was a radical misconception. At first sight it appears that this gives them a powerful case, for we find in the report that the commission calls up the idea of “something more than merely nominal.” If this expression truly reflects the basis of the decision there is reason for the court to interfere. Whilst acknowledging the force of this argument, I have come to the conclusion that it gives too little weight to the reasoning of the commission as a whole, and to the examination of the facts which the commission deemed necessary in both the instant reference and in the Badgerline case.”