Illegal (A 'Cannabis warning', that is kept on a police record, but does not show in CRB checks and carries no fine, is often given for possession of under an ounce herbal cannabis intended for personal use.)
Cannabis is the most widely used illegal plant in the United Kingdom. It is a plant which is native to the British Isles called hemp in natural form, The traditional name in Britain for Cannabis was hemp and that name is still used in the United Kingdom, although nowadays it refers almost exclusively to the non-psychoactive strains of the plant typically cultivated by growers and processors of industrial cannabis. The word cannabis is contemporaneously used as a generic term for plants and plant products deliberately grown for, or because of, their psychoactive properties; that is, the ones that can 'get you high'. A number of organisations advocate a reform of its legality, such as NORML UK, UKCSC, Drug Equality Alliance, Cannabis Law Reform, United Patients Alliance Feed The Birds and Cannabis Activists UK (via Facebook), while other organizations such as the Centre for Social Justice and Skunk Sense advocate that cannabis remains illegal.
According to the Home Office, "It remains illegal for UK residents to possess cannabis in any form". Giving evidence to 1997–98 parliamentary select committee hearings, the British Medical Association (BMA) said that users of cannabis for medical purposes should be aware of the risks, should enroll for clinical trials, and should talk to their doctors about new alternative treatments; but the BMA did not advise them to stop.
Cannabis is illegal to possess, grow, distribute or sell in the UK without the appropriate licences. It is a Class B drug, with penalties for unlicensed dealing, unlicensed production and unlicensed trafficking of up to 14 years in prison, an unlimited fine, or both. The maximum penalty is five years in prison. It is, however, worth noting that a "Cannabis warning" can be issued for small amounts of cannabis (generally less than 1 ounce of herbal cannabis, or a slightly higher quantity of hashish) if it is found to be for personal use. This entails the police keeping a record, albeit one which carries no fine and does not show up on standard CRB checks. From 2004 to 2009 it was a Class C drug.
In the survey-year ending March 2014, possession of cannabis offences accounted for 67% of all police recorded drug offences in the UK.