from a home office circular issued in 2012:-
The 2003 Police Regulations have been amended and the Police (Amendment No 2) Regulations 2012 are now in force.
Regulation 19(1)(d) of the 2003 Regulations has been amended so that any serving police officer selected in accordance with a regime of routine random testing may be required to provide a sample. This replaces the existing provision for the Secretary of State to specify categories of officers who may be tested.
Where testing is carried out because the Chief Officer has reasonable cause to suspect, on the basis of intelligence, that the officer has used a controlled drug, the determination now allows testing to cover one other controlled drug or drug group in addition to the five categories of controlled drugs currently set out in the determinations.