Some of the substances which are generically called 'illegal drugs', however, are much safer and self-limiting and many have virtually no harmful physical effects on the body (based on decades of clandestine use and research).
I'm refering to psychedelics and marijuana, drugs which I'm familiar with and have studied extensively through literature and some self experimentation. Apart from being much safer, some of these drugs have major upsides, when used therapeutically and can cure illnesses that modern medicine is unable to cure.
And if used by brilliant people to start with, they have the power to transform society in unbelievable ways: the tech revolution was started by young, brilliant people who've been inspired by psychedelic trips or psychedelic music/art/culture, produced by the counterculture of the '60s.
Some drugs, like heroin or cocaine have both a big abuse potential and can be harmful to the body, although none are as destructive as alcohol. Rational and sensible recovery and detox programs, combined with unrestricted access to safer drugs (like marijuana) can reduce the risks associated with these 'hard drugs'.
Portugal decriminalized drug use due to the alarming rates of addiction to opiates among youth in 2001. As a consequence, the opiate addiction problem is pretty much under control there.
Nicotine is another extremely addictive substance, yet sensible policy and access to valid information has led a lot of people to quit using it due to health concerns in developed countries, although developing countries have seen a rise in nicotine use.
On the other extreme - countries which ban all kinds of drugs (including alcohol) are seeing strong religious domination, which leads to extremism and terrorism, so total prohibition of altered states of consciousness is also bad.
There is a great book, called 'Animals and Psychedelics' in which it is reported that most animals, including insects are using various plants to intoxicate themselves, even though those plants are not suitable as food. They just like to get stoned or high or drunk and go to great lengths to find their intoxicants.
We should accept once and for all that human beings seek and require altered states of consciousness and not treat drug use as a 'societal cancer', but rather try to understand - why do we do it ? Why do animals do it ? Is there a evolutionary benefit in it ? Are there good parts in getting high, besides having fun ?
