If you are not sure what a 'legal high' is just click on this link and see what the Shiva Head Shop in Greenwich has to offer. You can order over the internet - in perfect legality - Snow Blow, Jungle High Energy Pills ("will bring out your wild side"), Party Pills, Happy Caps ("will have you grinning from ear to ear") and Kratom which is a "highly potent stimulant" that they claim is "not for human consumption."

Legal Highs are cocktails of legal chemicals which imitate the effects of illegal narcotics. They are the new generation of party drugs. But they are very different to the illegal substances that everyone has heard of because they are constantly evolving - so they can always stay several steps ahead of the lawmakers.

Legal Highs were in the news last week when the Advisory Council on the Misuse of Drugs (ACMD) banned a drug with the street name of Mexxy (full name: Methoxetamine), a drug with similar properties to Ketamine. The report issued by ACMD states that the drug has been under observation since 2010 but they only banned it for 12 months (while they study it some more). Presumably the ban was rushed through because of the recent deaths of two people in Leicestershire, deaths that were attributed to Mexxy.

The banning of Mexxy is a good example of how the suppliers of legal highs manage to run rings around legislators in Britain and other EU Member states. The suppliers know that governments take years to study the effects of drugs and so they continually change the ingredients. There are hundreds of chemicals that can be used as ingredients and thousands of different combinations.

Another unusual thing about legal highs is that nobody seems to know where they are made. Michael Bird, a documentary filmmaker who has been studying the issue, believes that "disillusioned scientists in UK and Holland make up the recipes, which they pass on to producers in China."

Central Europe is often mentioned as a possible source of Legal Highs and one of the first developments in the sector was in 1974 when Hungarian chemist Kálmán Szendrei discovered the psychedelic properties of the cathiones class of drugs (from the khat plant). Poland is an example of a European country that has cracked down on suppliers of Legal Highs: last year the Polish authorities closed over 1,500 'head' shops that supplied legal highs.

Legal highs are more widespread in central Europe and important lessons can be learned by British authorities. In the UK, legal highs tend to be used by clubbers and people who want to experiment but in Romania, an EU Member State with a population of 20 million, traditional drugs such as heroin are in short supply and hard drug users are starting to use legal highs as a substitute.

Valentin Simionov, of Romania's Harm Reduction Network, told me that "most injecting drug users in Bucharest are now shooting Legal Highs. Detox units and emergency rooms are filled with legal high users. One doctor told me he misses heroin users."

Those working in the drugs-treatment sector say that legal highs are more dangerous than traditional drugs such as heroin because their composition is so unknown, making any kind of substitution treatment very risky. By comparison, the various treatments for heroin addiction are well known.

Pasquale Policastro of the University of Szczecin in Poland summed up the difficulty for governments: "The development of legislation on new drugs requires a remarkable combination of different skills."

Inputs from physicians, pharmacologists, psychologists, pedagogy experts, police and social authorities - not to mention politicians - must be coordinated in order to get a coherent response to legal highs.

Follow Rupert Wolfe-Murray on Twitter: www.twitter.com/wolfemurray