I wrote to Home Secretary Theresa May MP:

Dear Mrs May

I noted proposals in the Queen's speech to ban all new psychoactive substances ("legal highs"). I had some questions about the evidence behind the proposed ban which I hope you can address:

* What is the latest evidence of harm caused by new psychoactive substances ("legal highs")? The Daily Mail cited a Centre for Social Justice study saying that they are linked to 97 deaths in 2012, compared to just 12 in 2009 - how reliable is this data? Can you provide me with the latest official statistics and tell me how they are calculated?
* What is the evidence that a blanket ban on new psychoactive substances will reduce a) their use, b) the harm caused by their use? Do you have evidence that a blanket ban will be more effective than an approach where each new substance is assessed for harm, as is currently the case? I'd also like to know how the exemption for psychoactive substances that are legal and widely used, such as caffeine, will work - do you have evidence on how this will impact their use, or do you plan to collect evidence on this?
* What impact has the ban on these substances in Ireland had, and have you assessed differences in the market in the UK?

I'm asking as part of the Ask for Evidence campaign, and plan to share your response publicly.

Many thanks and best regards

Prateek