Dangers of banning Spice and the synthetic cannabinoid agonists

Due to the use of Spice and similar products comprising herbal mixture sprayed with synthetic cannabinoid agonists [1], the UK Advisory Council on the Misuse of Drugs (ACMD), following some other countries, is advising that a range of synthetic cannabinoids become controlled drugs [2]. This makesmedical sense, because the effects of these chemicals are untested, unknown and some of
them may be dangerous. Moreover, banning dangerous pharmaceuticals has sometimes reduced use and harm in the past, for instance with gel formulation temazepam and barbiturates. Will this work when the drugs to be banned are being sold only because the ‘safer’ equivalent—cannabis—is not licensed in the United Kingdom for medical (or recreational) use and was re-classified recently as more dangerous against the advice of the ACMD?