P contended that a policy that forced prisoners to be outside their cell while their legally privileged correspondence was examined was unlawful. He sought judicial review of the policy which the HL granted. The policy was also contrary to ECHR art 8 but could be struck down under English law without resorting to the convention.
Lord Bingham: The policy infringes P’s right to confidential legal exchange with his lawyer. He recognises the ECtHR’s observances about the need to grant effective remedies where ECHR articles have been breached and that Wednesbury doesn’t always provide for this. He agrees with Lord Steyn’s observances.
Lord Steyn: Differences between proportionality and Wednesbury unreasonableness/ irrationality: (1) The former requires the court to asses the actual balance struck by DM, and not merely whether it was within a range of reasonable alternatives; (2) The former may require attention to be directed to the relative weight accorded to interests and considerations; and (3) even the “heightened scrutiny” version of Wednesbury unreasonableness developed in ex parte Smith is not as intense as proportionality and not sufficient to meet the requirements of the ECHR. Therefore it is important that that the correct level of review is adopted where ECHR rights are concerned. “This does not mean that there has been a shift to merits review”. He quotes Laws LJ in Mahmood as correctly saying that “the intensity of review in a public law case will depend on the subject matter in hand”. He concludes with “In law context is everything”. NB He has stopped short of calling for the wholesale replacement of Wednesbury with proportionality and has maintained that they both have a role to play. This perpetuates the confusing position of the law that Lord Slynn and Dyson LJ railed against (see above).
Lord Cooke: “I think that the day will come when it will be more widely recognised that Associated Provincial Picture Houses Ltd v Wednesbury Corpn  1 KB 223 was an unfortunately retrogressive decision in English administrative law, in so far as it suggested that there are degrees of unreasonableness and that only a very extreme degree can bring an administrative decision within the legitimate scope of judicial invalidation. The depth of judicial review and the deference due to administrative discretion vary with the subject matter. It may well be, however, that the law can never be satisfied in any administrative field merely by a finding that the decision under review is not capricious or absurd.”