A few points
The illegality of a substance and the level of that illegality does not stop people from taking it. Fact.
'Why is that a fact?' I hear you cry (after putting down your copy of the daily mail). Well.. millions of ecstasy tablets are taken every weekend in the UK, despite it already being erroneously classed as one of the most serious drugs you can possess. Furthermore if you look at other countries with harsher penalties for drug possession than our own, drug use is still prevalent.
So, taken that prohibition of a substance does not prevent it's widespread use, what does it actually achieve?
It ensures that all the money from the lucrative business of supplying that substance is controlled by criminals. They pay no tax and they protect their business with extreme violence. Many make no distinction between who they sell to (so it is as easily available to young teenagers as adults) and are involved in many other types of illicit activities, funded by the money they make.
It ensures there is no control on quality. The aforementioned dealers want to make as much money as possible so there is a financial incentive for them to mix the substance(s) they are selling with whatever crap they can get away with to make more cash. Users also have no idea of how much to take, as the drug they have bought could be 1% pure or 100% pure. This means that people actually have little control over what they are taking, particularly as our caring sharing government refuse to let people actually get their purchase tested before they take it.
It means that there is a lack of proper information available to anyone wanting to minimise the risks when taking a drug. For example the government has frequently told people that the biggest risk of ecstasy is dehydration and to drink more water then usual. In fact drinking too much water is one of the biggest causes of ecstasy-related deaths.
It actually causes the 'gateway drug' effect that many like to throw around as a reason for keeping less harmful substances illegal. People who experiment with drugs like cannabis and ecstasy and find them relatively harmless are already breaking the law and buying them from a dealer who may well sell other things. In their mind the government has said that crack is no worse than ecstasy. They've tried E's and it was fine, so why not give crack a go?
It criminalises millions of people that are (in most cases) otherwise law-abiding. People that are active, contributing members of society face arrest and potentially imprisonment for doing something that in most cases has little or no negative impact on others.
It discourages people that take a substance and do develop a problem from seeking help. The possibility of arrest and the social stigma attached to drug use means that people often do not seek help until the problem has become very serious, possibly life-threatening.
So in conclusion - What does the current drug classification system do?
1) It costs us all money as the billions made from taxing these substance could fund a decrease in other taxes.
2) It puts our children at risk by creating a black market that is as available to them as anyone else and ensuring they can't get proper information on the risks involved.
3) It puts anyone using the drugs at risk as it means there is no control over what they are taking.
4) It puts non-users at risk by encouraging and financing armed criminals and gang violence. It also means that billions of pounds is spent on policing the law and prosecuting offenders, meaning that those resources are not spent on tackling other types of crime.
The 'war on drugs' cannot be won because it is a ridiculous political battle against our own citizens and human nature. It is time to end the war and seek a peaceful, diplomatic solution before it costs any more lives.