There are different approaches to dealing with drugs around the world. Some countries place a greater emphasis on law enforcement - while others do not.
Here is a snapshot of some of the systems in countries where the issue has prompted major public debates.
The British system revolves around the Misuse of Drugs Act 1971. This legislation classifies drugs into three groups - A, B and C. Class A drugs are the most harmful and include heroin and cocaine. Class B includes cannabis. Class C includes steroids and some tranquilisers.
Drugs which are classified are illegal for sale and consumption. That means it is a criminal offence to possess or sell the drugs, and the courts can fine and jail offenders or order some other form of community-based sentence.
The former Home Secretary, David Blunkett, downgraded cannabis from B to C - but that decision was reversed by one of his successors.
The past year has seen a tense debate between scientific advisers and ministers over the best way to approach the prohibition of some drugs, including so-called "legal highs".
Many of these laboratory-designed drugs have now been banned - and the new coalition government is planning legislation to temporarily ban new legal highs as they emerge on the market before scientific research into the effects has been completed.
Many people believe that some drugs are legal in the Netherlands because of the availability of cannabis - but the reality is more complicated. The Dutch system tolerates licensed "coffee shops", where people can buy small amounts of cannabis for personal consumption. But the trafficking and sale of drugs remains illegal.
In effect, the Dutch have a system where cannabis sales are decriminalised in an effort to separate out its consumption from other drugs on the market.
In 2001, Portuguese law was changed to decriminalise the possession of small amounts of proscribed drugs for personal use. If police discover someone carrying a small dose of a drug, they will confiscate the substance and refer the user to a "Dissuasion Commission". This body assesses their level of addiction, and the appropriate education or treatment required. In other words, the state treats a user less like a criminal and more like a patient.
The Portuguese government claims that under the system there has been a decrease in deaths and the number of people being treated for addictions has risen.
The US led the way on the prohibition of drugs when former President Richard Nixon declared a "war on drugs". The federal system in the US is essentially the same as in the UK - harmful drugs are banned, and possession or trafficking results in a criminal charge.
However, the picture is complicated by the power of states to pass their own laws. Thirteen states, led by California, have decriminalised the consumption of cannabis for medicinal purposes - although in some cases the law conflicts clearly with federal legislation.
The bigger picture is the US government's role in attempting to contain the flow of drugs from South America - and also Afghanistan - into North American and Europe.
This country is at the heart of the US government's international efforts on combating drug production and trafficking - a great deal of money has been spent targeting the cartels.
But internally, Colombia's judges decided in 1994 that it was unconstitutional to punish people for possessing small amounts of drugs for personal use.
The government of former President Alvaro Uribe, a staunch US ally who stepped down earlier this month, won support to reverse the court's decision by changing the constitution. The new law aims to force addicts into treatment, rather than allow their imprisonment.