Dangers posed by mephedrone need rational response

But what Nutt should really be remembered, and celebrated, for is his refusal to be driven to knee-jerk comment and reaction.

He based his considerations of the harms caused by the misuse of different substances on evidence, and even debated those harms in relation to other harms that are widespread in society.

We have had protracted debates about the dangers of cannabis and ecstasy. Now there is a sudden debate about mephedrone following the death of two young men. There have been calls for its immediate criminalisation. This is a natural, but both irresponsible and inappropriate, response.

It is irresponsible because, despite the tragedy, society has to ensure that it does not make policy on the back of exceptional high-profile cases.

We need to reflect more carefully on the nature of the usage that caused the deaths - mephedrone was apparently mixed with alcohol, and possibly methadone. Further criminalisation of substance misusers might create ultimately greater harm to individuals than the use of mephedrone itself. We also need to consider the harms caused by its use compared to the consumption of alcohol and tobacco, and indeed in relation to other harms that may flow from people seeking other forms of "legal highs", such as extreme sports.

It is inappropriate because manufactured highs such as mephedrone have almost infinite possibilities of adaptation in ways that would probably enable young people to get round any law prohibiting its use.

We have to think of better ways: encouraging young people to take up safer risks that are not tantamount to a potentially fatal lottery arising from ignorance about the content and the consequences of a drug few of us had heard of just a few months ago.