New psychoactive substances are controlled in the United Kingdom based on an individual listing system (by means of a standard procedure), supplemented by a generic system. The legal basis establishing this system is s.2 of the Misuse of Drugs Act, combined with subsequent regulations. The Misuse of Drugs Act 1971 (MDA) is the main law regulating drug control in the United Kingdom. The list of controlled substances included in the Misuse of Drugs Act is divided into three parts (A, B, C). Since 2005 several NPS have been added to the list of controlled substances included in the Misuse of Drugs Act. Ketamine was initially controlled as a Class C drug in 2005 (see The Misuse of Drugs Act 1971 (Amendment) Order 2005 No. 3178) but it was reclassified as Class B drug in 2014 (see The Misuse of Drugs Act 1971 Amendment) Order 2014 No. 1106). 1,4-butanediol and BZP were added to the list of Class C drugs in 2009 (see The Misuse of Drugs Act 1971 (Amendment) Order 2009 No. 3209). Mephedrone was placed under control as a Class B drug in 2010 (see The Misuse of Drugs Act 1971 (Amendment) Order 2010 No 1207) but it was removed from the schedule in 2011 (The Misuse of Drugs Act 1971 (Amendment) Order 2011 No. 744) as it is considered to fall under control along with the group of synthetic cathinones, based on the generic definition in paragraph 1(aa) Part 2 of Schedule 2 to the 1971 Act as amended (Amendment) Order No 1207 of 2010. In May 2014, Khat was placed under control as a Class C drug under the Misuse of Drugs Act (see The Misuse of Drugs Act 1971 (Amendment) Order 2014 No. 1352 of May 27th 2014).

In January 2015, the Misuse of Drugs (Designation) (Amendment) (No. 3) (England, Wales and Scotland) Order 2014 amended the Misuse of Drugs (Designation) Order 2001 to “designate” the synthetic opioid AH-7921, the LSD-related compounds and the compounds captured by the extended definition of tryptamines as controlled drugs to which section 7(4) of the Misuse of Drugs Act 1971 applies. This means that it is unlawful to possess, supply, produce, import or export these drugs except under a Home Office licence for research or “other special purpose”. The Misuse of Drugs (Amendment No. 3) (England, Wales and Scotland) Regulations 2014 (“the 2014 Regulations”) amended the Misuse of Drugs Regulations 2001 (“the 2001 Regulations”) to add the synthetic opioid AH-7921, the named LSD-related compounds and the compounds captured by the extended definition of tryptamines to Schedule 1 (see here).

In February 2015 (effective in March 2015) the Misuse of Drugs (Designation) (Amendment) (England, Wales and Scotland) Order 2015 amended the Misuse of Drugs (Designation) Order 2001 to “designate” MT-45 and 4,4’-DMAR as controlled drugs to which section 7(4) of the 1971 Act. Accordingly, the Misuse of Drugs (Amendment) (England, Wales and Scotland) Regulations 2015 amended the Misuse of Drugs Regulations 2001 (“the 2001 Regulations”) by adding MT-45 and 4,4’-DMAR in Schedule 1 (see here).