Media Briefings


  • Published Date: April 2013

A temporary policy of removing penalties for possessing cannabis in the London borough of Lambeth increased the number of admissions to hospital for hard drugs. The rise in admission rates was particularly concentrated among men under 35 with no previous admissions to hospital for drug or alcohol abuse.


These are the key findings of research by Elaine Kelly and Imran Rasulpresented at the Royal Economic Society’s 2013 annual conference. Their work suggests that police strategies towards drug prevention and enforcement can have important and long-lasting effects on public health.


The researchers use NHS hospital records to assess the effect on population health of a policy that removed penalties for the possession of cannabis in the London borough of Lambeth from July 2001 to July 2002 – a policy known as The Lambeth Cannabis Warning Pilot Scheme’.


The study then compares drug-related admission rates in Lambeth to those in the rest of London, where cannabis policy had not changed. The focus is on admissions for Class-A drugs (opium, cocaine and methamphetamines), as admissions to hospital for cannabis are extremely rare.


The study finds that:


The policy increased the number of men admitted to hospital because of hard-drug use by 40-100% of their pre-policy levels.


The effects were concentrated among men aged 15-34 when the policy began.


The average length of stay for Lambeth residents admitted to hospital for Class-A drugs rose by 20-40%, suggesting that average case was more severe.


For some cohorts, hospital admissions remained higher six years after the policy ended.


The policy had some spillovers on neighbouring boroughs, which experienced smaller but significant rises in drug admission rates.


The increase in drug-related hospital admittances may lend support to the argument that cannabis acts as a gateway drug to harder drugs.


Many countries, including the Netherlands, Portugal and Spain, have moved away from an illicit drugs strategy based on enforcement and punishment and towards policies that focus on prevention, education and treatment. The authors comment:


‘Our study illustrates that liberalising enforcement on its own can have negative consequences for population, which should be taken into account when designing an overall drugs strategy.



Illicit drug use generates substantial costs to the economy and society, through crime, ill health and diminished labour productivity. Governments across the world have therefore put in place regulations to curb both drug use and its negative consequences.


But there is a debate about the relative weights that should be given to prevention, enforcement and treatment. The current trend is away from enforcement and punishment and towards prevention and treatment. Spain, Portugal and several US states have all recently reduced sanctions for drug possession, and a number of Latin American countries are debating whether to follow suit.


This research explores the effects on population health of temporarily reducing police enforcement of punishments for possession of cannabis, while leaving all other elements of the drugs strategy unchanged.


The study examines the impacts on drug-related hospital admissions of the Lambeth Cannabis Warning Scheme (LCWS), which temporarily depenalised the possession of small quantities of cannabis, so that this was no longer a prosecutable offence.


The policing experiment took place in the London Borough of Lambeth and ran from July 2001 to July 2002, during which time policing policy in all other London boroughs did not change.


The effects on drug-related hospital admissions are estimated using NHS administrative admission records. Changes in admission rates for Class-A drugs in Lambeth are compared with admission rates in the other 31 London boroughs. Admission rates are split by sex, age, and previous drug and alcohol admission history.


The focus is on Class-A drugs rather than cannabis, as hospital admissions for cannabis are extremely rare. Class-A drug admissions will be affected by the LCWS if the policy affects the price or availability of Class-A drugs or if cannabis operates as a stepping-stone to harder drugs.


The principal results of the policy are four:


First, relative to other London boroughs, the depenalisation policy increased admission rates for Class-A drugs by 40-100% relative to pre-policy levels. The effects were concentrated in men aged 15-34 when the policy began.


Second, the impacts of the policy on admission rates are long-lived. There were higher admission rates among some age groups up to six years after the LCWS had ended.


Third, the policy generated spillovers in neighbouring boroughs, where there were also smaller but significant rises in drug admissions. These spillovers were again concentrated among younger cohorts without prior histories of hospital admissions related to the use of illicit drugs or alcohol.


Finally, in addition to an increased number of admissions, the average length of stay for Lambeth residents admitted to hospital for Class-A drugs rose by 20-40%, suggesting that the average episode was more severe.


Taken together, the results from the study indicate that policing strategies towards the market for drugs can have significant and long-lasting impacts on public health. More liberal approaches to enforcement can help free up resources in the criminal justice system. But these strategies may need to include improved prevention or treatment programmes if they are to avoid damaging the health and wellbeing of the population.





Notes for editors:


Policing Cannabis and Drug Related Hospital Admissions: Evidence fromAdministrative Records by Elaine Kelly and Imran Rasul




Elaine Kelly: +44 (0)7715 266055,


RES media consultant Romesh Vaitilingam:

+44 (0) 7768 661095