24/06/2015 13:42 BST | Updated 24/06/2016 06:59 BST

The Government Has Been Trying to Play Catch-up on Drug Control - Now They Have Lurched to Banning Everything

Liberal Democrats in the Lords are trying to rescue something from the car crash that is the government's Psychoactive Substances Bill by tabling a series of amendments.

The Bill seeks to make it illegal to produce or supply any substance that affects someone's mental functioning or emotional state, unless the government specifically exempts it.

This takes the "my substances of choice, like alcohol and tobacco, are OK but yours aren't" approach to a new level.

On Tuesday we tried and failed to press the pause button while an independent, evidence-based review (posh phrase for 'what works in practice?') of existing laws was carried out.

The UK Bill is based on a similar Act in force in the Republic of Ireland for the past four years that has been so disastrous, the Irish are thinking of repealing it.

At the moment 'head shops' sell so-called 'legal highs' with impunity. The government has been trying to play catch-up, banning harmful new substances as they are developed, and losing.

They have now lurched, with Labour Party support, to banning everything.

Evidence that the market is demand-driven is overwhelming - people are only buying synthetic cannabis and artificial ecstasy because the real things are banned, even though the real things are potentially far less harmful.

Far from curing the problem, the evidence from Poland and Ireland, where bans are in place, is that making the production and supply of new psychoactive substances illegal simply pushes the problem underground.

Further evidence that this is the real agenda comes from the fact that the government rhetoric, that all new psychoactive substances are dangerous no matter what they are and how much you take, is coupled with a failure to make personal possession of them illegal.

So the police cannot stop and search you if you have an EX-1 (artificial ecstasy) in your pockets because it is not an offence but they can if you have a real ecstasy tablet. How exactly the police are supposed to know the difference is anyone's guess ?

Of course not all psychoactive substances, whether controlled under the Misuse of Drugs Act, covered by this Bill or are exempt from the Bill like alcohol, are not dangerous if they are used sensibly.

Indeed the government's decision not to criminalise possession under this Bill on the grounds that to do so would be 'disproportionate' is an acknowledgement of that fact, even if the rhetoric contradicts that approach.

The Liberal Democrats, supported by back-benchers from the other political parties and the independent crossbenches, are trying to get the government to exempt low risk substances, licence responsible 'head shops' and extend the proportionate approach to drugs possession to all psychoactive substances, including those controlled by the Misuse of Drugs Act.

If we are really serious about reducing the harm caused by drugs misuse, we must have a legal framework that has credibility in the eyes of those who use, or could potentially use, psychoactive substances.

We also need to place the emphasis on reducing demand through credible education rather than, as at present, spending the overwhelming majority of available resources on trying and failing to reduce the supply side.

Lord Paddick is a Lib Dem peer and a former Met Police deputy assistant commissioner