establishing that the order was invalid or defective, basically showing that the minister had not acted in good faith Perhaps the House of lords would today differ from the majority in Liversidge by holding that, in the absence of any explicit statutory indication to the contrary, a detainee is entitled to a hearing at which he can contest the grounds for his detention and perhaps even to reasons for a decision to continue to detain him. But unless the grounds revealed at the hearing or the reasons given disclosed that either the policy or the decisions in terms of that policy are perverse, one which no reasonable minister advising the Crown could in the circumstances reasonably have held, the Court, as the House of Lords in Rebman tells us, uld not The perversity test is the test of w ednesbury unreasonableness, articulated by lord greene MR in Asociated prorincial picture Houses Ltd r Wednesbury Corporation. Lord Greene said that discretions were reviewable when unreasonably exercised, where unreasonableness means that the act isso absurd that no sensible person could ever dream that it lay within the powers of the authority. To illustrate what he meant by absurdity, Lord Greene adopted the example of the red-haired teacher, dismissed because she has red hair'. Now, Wednesbury unreasonableness is often thought of as an important step in the development of the modern law judicial review because it suggested that there were controls on discretionary authority. But, as Stephen Sedley has pointed out, we should not regard Wednesbury as a'sudden flash of light representing the 'modern sea change in public law, but 81948 1 KB 223, hereafter wednesbury14 establishing that the order was invalid or defective, basically showing that the minister had not acted in good faith. Perhaps the House of Lords would today differ from the majority in Liversidge by holding that, in the absence of any explicit statutory indication to the contrary, a detainee is entitled to a hearing at which he can contest the grounds for his detention and perhaps even to reasons for a decision to continue to detain him. But unless the grounds revealed at the hearing or the reasons given disclosed that either the policy or the decisions in terms of that policy are perverse, ‘one which no reasonable minister advising the Crown could in the circumstances reasonably have held’, the Court, as the House of Lords in Rehman tells us, would not review. The perversity test is the test of Wednesbury unreasonablenesss, articulated by Lord Greene MR in Associated Provincial Picture Houses Ltd v Wednesbury Corporation. 18 Lord Greene said that discretions were reviewable when unreasonably exercised, where unreasonableness means that the act is ‘so absurd that no sensible person could ever dream that it lay within the powers of the authority.’ To illustrate what he meant by absurdity, Lord Greene adopted the example of the ‘red-haired teacher, dismissed because she has red hair’.19 Now, Wednesbury unreasonableness is often thought of as an important step in the development of the modern law judicial review because it suggested that there were controls on discretionary authority. But, as Stephen Sedley has pointed out, we should not regard Wednesbury as a ‘sudden flash of light’ representing the ‘modern sea change in public law’, but 18 [1948] 1 KB 223, hereafter Wednesbury