Misuse of Drugs Act 1971: Drug Classes, Penalties, and Defences

The Misuse of Drugs Act 1971 is the UK’s main law on controlled substances. It sorts every restricted drug into one of three classes — A, B, or C — according to how harmful it is considered when misused, and the class fixes the maximum penalty a court can impose for possessing, supplying, or producing that drug.¹ Ceilings run from two years in prison for possession of a Class C drug to life imprisonment for supplying a Class A drug.²

What’s in Each Class

Schedule 2 of the Act lists every controlled substance and places it in one of the three parts.³ The list is not fixed: drugs move between classes as evidence changes.

Class A is reserved for the substances Parliament treats as most harmful. Heroin, cocaine, MDMA (ecstasy), LSD, methadone, and methamphetamine all sit here, along with magic mushrooms containing psilocin or psilocybin.³ One wrinkle catches people out: amphetamine is normally Class B, but any amphetamine prepared for injection is treated as Class A.

Class B covers cannabis, amphetamines in non-injectable form, ketamine, synthetic cannabinoids, and codeine. Cannabis is the most commonly encountered Class B drug, and its classification has shifted with policy: it was moved to Class C in 2004 and back to Class B in 2009.

Class C contains drugs assessed as less harmful than those above but still carrying real risks. Benzodiazepines such as diazepam (Valium) and temazepam sit here, along with anabolic steroids and GHB. Khat was added to Class C in June 2014.⁴ A specific carve-out applies within Class C: personal possession of anabolic steroids is not a criminal offence, though supplying or importing them for others is.²

Penalties for Possession

Schedule 4 of the Act sets out the ceilings in full.⁵ For simple possession, the maximum sentences on indictment are:

Class A: up to 7 years in prison, an unlimited fine, or both.
Class B: up to 5 years in prison, an unlimited fine, or both.
Class C: up to 2 years in prison, an unlimited fine, or both. Anabolic steroids for personal use are the exception and are not an offence.

Those are the Crown Court ceilings. A magistrates’ court can impose a maximum of 12 months for Class A possession and 3 months for Class B or C.⁵ Statutory maximums are rarely reached in practice; courts weigh the amount involved, your role, and any previous convictions.

Penalties for Supply, Production, and Possession With Intent to Supply

Class A: up to life imprisonment, an unlimited fine, or both.
Class B: up to 14 years in prison, an unlimited fine, or both.
Class C: up to 14 years in prison, an unlimited fine, or both.

The identical 14-year ceiling for Class B and C supply is deliberate: Parliament wanted the same hard limit on dealing regardless of whether the drug is cannabis or a benzodiazepine.²

A conviction brings consequences beyond the sentence. An unspent conviction can block you from certain jobs, and in roles requiring enhanced background checks — working with children, in healthcare, or in financial services — even spent convictions may be disclosed.

Cannabis Warnings and the Escalation Ladder

Most cannabis possession cases in England and Wales never reach a courtroom. Police operate a three-stage escalation for adults caught with small amounts for personal use.⁶ A first offence with no aggravating factors usually produces a cannabis warning: a verbal caution given on the street or at a station, with no arrest and no criminal record from the warning itself.

A second offence typically brings a penalty notice for disorder (PND) carrying a £90 fine. Pay within 21 days and the matter is closed. A third offence triggers arrest and formal prosecution.⁶ This graduated approach applies only to cannabis. Possession of a Class A drug, even a small personal amount, follows a different and more serious path.

Defences That Can Defeat a Charge

The Act contains two statutory defences worth knowing even if you were caught with the drug on you.

Section 28 gives you a complete defence if you can prove you neither believed, suspected, nor had any reason to suspect that the substance was a controlled drug.⁷ Someone slipping drugs into your bag without your knowledge is the standard example. The defence also covers a genuine belief that what you had was a different, lawful substance.

Section 5 adds a second defence. If you found a controlled drug and took possession of it to stop someone else committing an offence, or to hand it to someone authorised to take custody, you have a defence, provided you took reasonable steps to destroy it or deliver it to the authorities as soon as possible.⁸ Holding onto found drugs “for safekeeping” without contacting the police will not qualify.

Classes Versus Schedules: Why They Are Not the Same

Classes decide criminal penalties. Schedules decide medical access. People regularly confuse the two, so the distinction matters when reading about UK drug law.

Alongside the Act, the Misuse of Drugs Regulations 2001 place every controlled drug into one of five schedules.¹ The schedule governs whether the drug can be prescribed, and how it must be stored, dispensed, and recorded.

Schedule 1 drugs have no recognised medical use in the UK (LSD, raw cannabis, MDMA). Possession needs a Home Office licence; a doctor cannot prescribe them.
Schedule 2 drugs have accepted medical uses but a high abuse risk (morphine, diamorphine, fentanyl, and, since November 2018, cannabis-based products for medicinal use). Prescribing and record-keeping rules are strict.
Schedule 3 drugs have medical uses and a lower abuse risk than Schedule 2 (temazepam, midazolam, buprenorphine). Prescribing is still regulated; record-keeping is lighter.
Schedule 4 is split in two. Part I covers benzodiazepines such as diazepam. Part II covers anabolic steroids, which are exempt from the prohibition on personal possession.
Schedule 5 covers preparations with very low concentrations of controlled drugs (some cough medicines containing small amounts of codeine). These face the fewest restrictions and can often be bought over the counter.

A single drug can sit in one class and a different schedule. Diazepam, for instance, is Class C for penalty purposes but Schedule 4 for medical access.⁹

Temporary Class Drug Orders

New psychoactive substances appear faster than the full classification process can respond. The Police Reform and Social Responsibility Act 2011 gave the Home Secretary power to issue a Temporary Class Drug Order, bringing an emerging substance under immediate control.¹⁰

A Temporary Class Drug Order lasts up to 12 months, during which the Advisory Council on the Misuse of Drugs conducts a scientific review.¹¹ While the order is active, importing, exporting, producing, and supplying the substance all carry the same penalties as for established controlled drugs. At the end of the 12 months the substance is either permanently classified or the controls lapse.

One point to note: simple possession of a temporary class drug is not a criminal offence.⁸ Police can seize and destroy the substance, but they cannot arrest or prosecute solely for having it. The policy intent was to target suppliers of unknown substances without criminalising users before the science was settled.

What the Act Does Not Cover: the Psychoactive Substances Act 2016

The 1971 Act works from a named list. If a substance is not in Schedule 2, it is not controlled under this Act, even if it produces similar effects. That gap was closed by the Psychoactive Substances Act 2016, which prohibits producing, supplying, or importing any substance capable of producing a psychoactive effect, with exemptions for alcohol, tobacco, nicotine, caffeine, food, medicinal products, and drugs already controlled under the 1971 Act.¹²

The maximum penalty for supply or production under the 2016 Act is 7 years on indictment, and simple possession is generally not an offence.¹³ The two Acts run in parallel: named drugs fall under the 1971 Act, while new or unnamed psychoactive substances are caught by the 2016 Act.

How Drugs Move Between Classes

Section 1 of the 1971 Act established the Advisory Council on the Misuse of Drugs (ACMD) as an independent body advising the Home Secretary on which substances should be controlled, reclassified, or removed.¹⁴ Its assessments drive virtually every classification decision: cannabis moving from Class C back to Class B, khat entering Class C, and the addition of new synthetic drugs to the schedules.

Members are appointed by the Home Secretary for three-year terms and can serve up to ten years in total.¹⁵ The Act requires the council to include professionals from medicine, pharmacy, and related sciences. The Home Secretary is not legally bound to follow the ACMD’s recommendations, and the gap between advice and action has produced some of the most publicly contentious moments in UK drug policy, including the dismissal of Professor David Nutt as ACMD chair in 2009 after he publicly stated that ecstasy and cannabis were less dangerous than alcohol and tobacco. The council also monitors emerging drug trends and can trigger the Temporary Class Drug Order process when a substance appears to pose an imminent risk.

1
GOV.UK. Circular 001/2024: Control of 20 New Drugs
2
GOV.UK. Drugs Penalties
3
Legislation.gov.uk. Misuse of Drugs Act 1971
4
GOV.UK. Circular 011/2014: Changes to Misuse of Drugs Act 1971 – Khat
5
Legislation.gov.uk. Misuse of Drugs Act 1971 – Schedule 4
6
College of Policing. Possible Justice Outcomes Following Investigation
7
Legislation.gov.uk. Misuse of Drugs Act 1971 – Section 28
8
Legislation.gov.uk. Misuse of Drugs Act 1971 – Section 5
9
Legislation.gov.uk. The Misuse of Drugs Regulations 2001
10
Legislation.gov.uk. Police Reform and Social Responsibility Act 2011 – Schedule 17
11
GOV.UK. Temporary Class Drugs Factsheet
12
Legislation.gov.uk. Psychoactive Substances Act 2016
13
Legislation.gov.uk. Psychoactive Substances Act 2016
14
Legislation.gov.uk. Misuse of Drugs Act 1971 – Section 2
15
GOV.UK. Membership – Advisory Council on the Misuse of Drugs