Mr McMahon QC for the appellants put forward that the wording of Article 61(8)(b) was clear and unambiguous; that an approved device must be used and therefore that evidence obtained through the use of an unapproved device rendered the evidence inadmissible.
Lord Hughes in his judgment addressed the admissibility of evidence, particularly when obtained through unlawful means; the intended consequence Parliament had in mind of not using an approved device; and similar provisions (and differences in process) for other devices such as traffic speed gun and breathalyser test devices.