POLICE smart when they hear the term "legal highs".

The term cropped up a few years ago to describe the new generation of synthetic drugs designed to mimic the effects of prescribed substances. Since then some of them have been banned.

Others have emerged. Those responsible for policing the market in illicit and semi-illicit products are almost past caring about such legislative niceties.

"There is too much focus on the words 'legal' or 'illegal'," said Detective Chief Superintendent John Cuddihy. "Let's focus on the harm these substances cause, then we can see their true effect."

Police and policy-makers prefer the term new psychoactive substances - a catch-all that includes the whole gamma of products on the market.

But the irony is sometimes the drugs being passed off as, say, legal plant food in fact contain prescribed substances, such as amphetamines. And sometimes people buying what they think are proper drugs, such as cocaine, are actually being duped with near worthless powder. Hence last week's Global Drugs Survey revealing Scottish cocaine users thought the drug was very poor value for money.

Police watch the movements of some of the chemicals used as the precursors or adulterants of drugs, whether theoretically legal or not.

Cocaine dealer Hugo Young was last year convicted - despite having no cocaine - after he was found with 26 kilos of benzocaine, one of its best known adulterants. Other chemicals they look out for include, lactose, used to cut amphetamines.

Mr Cuddihy said: "Why, for example, would anyone have a tonne of lactose, a dairy product, in a high rise flat? Do they have a herd of cows?"

Scientists, meanwhile, are studying new ecstasy-style pills, such as Mortal Kombat, linked with the death of Regane MacColl, 17, from Clydebank, in February.