The UK is to opt out of planned European Commission rules on so-called "legal highs".
Home Office minister Norman Baker said joining the scheme would "fetter" attempts to ban new drugs coming on to the market.
But he said this did not "diminish our commitment" to tackling the problem.
Legal highs, officially known as psychoactive substances, are synthetic drugs which can be bought online and sometimes in shops.
They are often created in laboratories in the Far East and are are rushed to European and other markets before authorities have time to ban them.
Disputes EU's claim
Several deaths have been linked to legal highs. More than 200 of the substances have been banned since the coalition came to power in 2010.
But the government says the EU's planned directive would be too unwieldy to deal with the fast-changing situation.
In a statement, Mr Baker insisted the decision to opt out "should not in any way be considered to diminish our commitment to tackle this issue".
He added: "The coalition government is conducting a review into new psychoactive substances, and alongside our programme of work, we are looking at a range of options including legislative ones to enable us to deal with the dangers many of these substances present even more speedily and effectively."
Mr Baker added that the government "strongly" disputed "the evidence base stated in the EU Commission's impact assessment which estimates that 20% of new psychoactive substances have a legitimate use".