A draft for a post I'm writing for the Fabian Society. Feel free to offer suggestions or such.
______________________________________________Britain's Drug Policy - Time for Change?
Prior to the 20th century, the UK had little to no regulation of drugs or narcotics - it was only after World War 1 that the move towards prohibitionism began. Cocaine and opium were the first drugs to be controlled, and this was extended to cannabis in 1928. As the drug market continued to change and evolve, this eventually led to the Misuse of Drugs Act of 1971 that still shapes UK drug laws to this day. Although new drugs have been added (such as psilocybin) and other drugs have changed in status (cannabis went from Class B to Class C in 2004, and then back in 2009), this act must be the main focus of any discussion on the governments attitude towards this issue.
The War on Drugs is, first and foremost, unenforcable. Cannabis has become the largest black market good in the world, followed by prostitution. Class A drug usage has increased rather than fallen - more than half a million young people were found to have used cocaine or ecstacy in 2009.  It is clear that police resources are being stretched fighting a war that can never be won.
The Misuse of Drugs Act itself makes little real sense. Class A sees highly addictive and lethal drugs such as heroin or crack placed alongside "soft drugs" such as LSD or MDMA that have few deaths related to their usage. Cannabis, a drug with no recorded deaths at all and few proven detrimental effects to health is in Class B while the dissociative drug ketamine is in Class C. And the drug that was found to be most harmful of all in terms of both damage to the user and the community is completely legal and easily purchasable. In 2007, David Nutt, a former government drug adviser published a report in the Lancet proposing a new system of drug classification based on harm.  Alcohol came first on the scale of 1 to 100 with a score of 72, beating out both heroin and crack (55 and 54 respectively). Cocaine scored 27, MDMA 9 and bottom of the list, with a harm figure of just 5, were psilocybin mushrooms. Nutt was eventually sacked in October 2009 for claiming that cannabis (which had just been put back into Class B) was less harmful than alcohol or tobacco. The hypocrisy within government drug policy is one of the greatest flaws in the War on Drugs and especially in harm reduction policy as it makes drug users all the more sceptical of health warnings from the government.
Perhaps most importantly of all is the argument that the War on Drugs itself is in fact a war on personal freedom. Drug possession is essentially a victimless crime - in most cases, the only victim of the substance is the user themself if they choose to use it irresponsibly. In this case, it is purely the choice of the individual to use drugs - the only harm usually involved in drugs is due to the related crime created by prohibition.
So what's the alternative? Some countries have begun to move towards more liberal drug policies - a famous example is the Netherlands where cannabis was legalized and regulated, available in 'coffee shops'. Contrary to the expectations of critics, who believed it would encourage drug use and lead to higher rates of consumption, cannabis use rates remain amongst the lowest in Europe - 9.5% of young adults consume soft drugs once a month, compared to 13.8% in the UK. 
Portugal took a radical step in 2001 by decriminalizing all drugs - a country with one of the highest hard drug use rates in Europe. While drugs were not made completely legal, punishment was replaced with treatment. The results were a resounding success - HIV infection rates dropped and the number of drug users seeking treatment skyrocketed. Drug usage rates, as in Holland, did not rise. 
However, while these are progressive steps towards a more sensible drug policy, perhaps the best solution would be to legalize ALL drugs. This would be preferable to decriminalization as it would remove supply from the dealers and would allow the state to purify, regulate, sell and tax the drugs. This would decrease deaths from drug use - many of which are caused by prohibition, due to the unpure nature of most illegal drugs - and would also allow for drug excise duties to be put towards treatment programs. There would also no longer be the need for as much spending on drug enforcement, and the problem of jail overcrowding would be lessened as the focus would be on treatment rather than punishment for drug users. Another source of income for crime will also have been wiped out.
The War on Drugs has come to be almost a carbon copy of 1920s Prohibition in the US. Supply fell into the hands of criminal rackets, the laws proved completely unenforcable and eventually the government allegedly began poisoning its own citizens in an effort to prevent consumption. . It's time for politicians to admit that punishment and enforcement of drug laws has failed, and a new approach is required.
 Nutt, D.; King, L. A.; Saulsbury, W.; Blakemore, C. (2007). "Development of a rational scale to assess the harm of drugs of potential misuse".