(1) The powers conferred by section 289 may be exercised only with the appropriate approval unless, in the circumstances, it is not practicable to obtain that approval before exercising the power.
(2) The appropriate approval means the approval of a judicial officer or (if that is not practicable in any case) the approval of a senior officer.
(3) A judicial officer means -
(a) in relation to England and Wales and Northern Ireland, a justice of the peace,
(b) in relation to Scotland, the sheriff.
(4) A senior officer means -
(a) in relation to the exercise of the power by an officer of Revenue and Customs, such an officer of a rank designated by the Commissioners of Customs and Excise as equivalent to that of a senior police officer,
(aa) in relation to the exercise of a power by an SFO officer, the Director of the Serious Fraud Office,
(ab) in relation to the exercise of a power by a National Crime Agency officer, the Director General of the National Crime Agency or any other National
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