AFAIK its a 2002 amendment to the Misuse of Drugs Act which brings it into line with similar legislation in other countries (particularly America).
In simple terms what it means is that a “new” drug which can be traced back to a previously illegal chemical takes the legal classification status of the original chemical.
So any “new” drug with an amfetamine base is either class B or class A, and anything with a piperazine base is a Prescription Only Medicine which it is illegal to sell (but not to possess).
The UK govt does appears to be investigating the possibility of making piperazine based recreational drugs class C, but it is still being debated by the Home Office and Department of Health (a similar situation occured with Ketamine, which was eventually made class C).
There may be loopholes if you are unlucky enough to get caught with a large amount (as what you are charged with depends on what the forensic analysis turns up) but it makes no difference to “street level” arrests and surveillance.
When cops catch people who are or who associate with ravers in posession of any “unidentified” pill or powder they automatically assume it is class A (and thus can exercise all the powers of search and seizure if they so wish) before doing any scientific tests….
