To promote the rule of law by have a rational approach to drug legislation that will be respected by the young people of the nation, whilst generating tax revenue that can be used to reduce the national debt or to fight the effects of more pernicious dangerous drugs, for example alcohol.
For too long the government's stance on drug regulation has been irrational, taking a misguided backward looking moral stance rather than understanding the scientific medical evidence. Prohibition has failed in the UK with regard to drugs as it did wit regard to alcohol in the 1930's USA. The War on Drugs is a sick joke and none of the foot soldiers involved i.e. the police, believed it can be won. Indeed with regard to cannabis this fight has been abandoned by the police.
I do not take illegal drugs, but it is plainly obvious to me that it would be preferable if those who wish to take soft drugs, in particular cannabis, should be able to obtain it through regulated licensed suppliers, where tax can be paid and the trade taken away from criminals. Concerning cannabis, when the governments own medical experts feel that this drug is less harmful than the legally allowed drug of alcohol there is something wrong with the law and the governments stance is simply aiding and abetting criminality.
By taking a liberal stance on the non harmful drugs the police will be able to concentrate on the fight against class A drugs.