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Misuse of Drugs Act 1971: Drug Classes, Offences, Defences and Police Powers

The Misuse of Drugs Act 1971 controls drugs in three classes, A, B and C, and makes it an offence to possess, supply, offer to supply, produce or cultivate them without authority. Section 23 gives police the power to stop and search for drugs, and section 28 gives a lack-of-knowledge defence. It is core law for the sergeants' exam and the NIE.

Updated 2026-10-30 · 11 min read · Checked against official sources

The Misuse of Drugs Act 1971 is short, but nearly every section produces an exam question. The examiner tests the difference between possession and control, what "supply" means, when someone is "concerned in" supply, what the section 28 defence really requires, and exactly what section 23 lets you search.

This guide sets out the Act for the sergeants' and inspectors' exams and the NIE, with the drug classes, penalties, powers and leading cases. For the search power in context, read it alongside our section 1 PACE guide. For the exam itself, see the sergeants' exam guide.

This guide is a revision aid, not legal advice; the exam follows the 2027 Blackstone's manuals, so check every point against your manual.

Misuse of Drugs Act 1971: the offences in full

Possession (section 5(2))

Section 5(1) makes it unlawful to have a controlled drug in your possession, subject to regulations (for example a prescription). Section 5(2) makes that an offence. Section 37(3) adds that the things in a person's possession include anything subject to their control which is in another person's custody.

Possession with intent to supply (section 5(3))

"…it is an offence for a person to have a controlled drug in his possession, whether lawfully or not, with intent to supply it to another…" (section 5)

Note "whether lawfully or not": a pharmacist lawfully holding a drug commits this offence if they intend to supply it unlawfully. The intent must be to supply in the future. Evidence of past supply points to a supply charge instead.

Production and supply (section 4)

Section 4(1) makes it unlawful to produce a controlled drug, or to supply or offer to supply one to another. Section 4(2) makes it an offence to produce, or be concerned in the production by another. Section 4(3) creates three supply offences:

  1. supplying or offering to supply a controlled drug to another;
  2. being concerned in the supplying of a controlled drug to another;
  3. being concerned in the making to another of an offer to supply.

Section 37 says "supplying" includes distributing, and "produce" means producing by manufacture, cultivation or any other method.

Cultivation, premises and opium (sections 6, 8 and 9)

  • Section 6: cultivating any plant of the genus Cannabis without authority.
  • Section 8: being the occupier, or concerned in the management, of premises and knowingly permitting or suffering production, supply or an offer to supply of any controlled drug, the preparation of opium for smoking, or the smoking of cannabis, cannabis resin or prepared opium. Smoking any other drug on the premises is not covered.
  • Section 9: offences relating to smoking or using prepared opium and opium pipes and utensils.

The drug classes in the UK

Schedule 2 to the Act sets the classes. The examples below were checked against the current Schedule 2 and the gov.uk drugs penalties page.

Class Examples
A Cocaine (including crack), heroin (diamorphine), MDMA (ecstasy), LSD, magic mushrooms, methadone, methamphetamine, fentanyl
B Cannabis and cannabis resin, amphetamine, ketamine, GHB and GBL, codeine, synthetic cannabinoids, synthetic cathinones such as mephedrone
C Benzodiazepines such as diazepam, anabolic steroids, khat, nitrous oxide, xylazine
Temporary class drugs New substances banned for up to a year while they are assessed. No possession offence, but supply and production carry 14 years

Key fact: Crack is cocaine for the purposes of the Act, because Schedule 2 covers any preparation or product containing a listed drug (R v Russell [1992]). Charge possession of the drug actually found, even if the defendant believed it was a different controlled drug.

Points to prove

Element What it means Evidence an officer gathers
Controlled drug A substance in Schedule 2 (or under a temporary class drug order) Forensic analysis, drug identification, continuity of exhibits
Possession Physical possession or control, with knowledge of possession of the item Where found, ownership of the bag, car or room, admissions, fingerprints or DNA
Unlawfully Not authorised by regulations or a licence Checks for prescriptions or licences
Intent to supply (s.5(3)) Intends to supply in the future Quantity, purity, deals or wraps, scales, cutting agents, phone messages, lists
Supply / offer (s.4(3)(a)) Handing over so the recipient can use it for their own purposes; an offer by words or conduct Test purchase, surveillance, messages, witness accounts
Concerned in (s.4(3)(b), (c)) Taking part in a supply or offer by another, even at a distance Phone data, cash, links to the supplier, roles in a line
Production / cultivation Manufacturing, growing or any other method Grow equipment, plants, power bypass, bills, admissions
Occupier or manager (s.8) Occupies or manages the premises and knowingly permits or suffers the activity Tenancy, keys, control over who enters, knowledge evidence

Mode of trial and maximum penalty

All the main offences are triable either way. These figures come from Schedule 4 as currently in force.

Offence Class A Class B Class C
Possession (s.5(2)) 7 years 5 years 2 years
Possession with intent to supply (s.5(3)) Life 14 years 14 years
Supply, offer, being concerned (s.4(3)) Life 14 years 14 years
Production, being concerned (s.4(2)) Life 14 years 14 years
Permitting premises to be used (s.8) 14 years 14 years 14 years
Cultivation of cannabis (s.6(2)) — 14 years —
Obstructing a search (s.23(4)) 2 years 2 years 2 years

The Sentencing Council supply guideline notes that supply and intent to supply become indictable only where the defendant could receive the minimum sentence of seven years for a third Class A trafficking offence under section 313 of the Sentencing Code.

Exam tip: The maximum for possession with intent to supply Class B and Class C is the same, 14 years. The class makes a difference for simple possession (5 years v 2 years), not for supply.

Key definitions and leading cases

Possession

CPS guidance on drug offences says possession needs physical possession or control plus knowledge that you possess the item, even if you do not know it is a controlled drug. That is why the section 28 defence matters: knowing you have a package is enough for possession, and the defence then deals with what you did not know about its contents.

Supply

  • R v Maginnis [1987]: supply needs more than a mere transfer of physical control. It means enabling the recipient to use the thing for their own purposes. Returning drugs to the person who deposited them can be a supply.
  • R v Denslow [1998]: where two people agree to buy drugs together, the one who hands over the other's share is technically supplying but will be dealt with as for simple possession.
  • R v Harris [1968]: injecting another person with that person's own drug is not supplying it. CPS guidance points to sections 23 and 24 of the Offences Against the Person Act 1861 (administering a noxious thing) instead.

Offers

  • R v Showers [1995]: an offer to supply can be made by words or conduct. The prosecution does not need to prove the defendant had the drugs or meant to supply them.
  • CPS guidance, citing R v Goodard [1992] and R v Mitchell [1992], says it is no defence that the substance actually supplied was different from what was offered, or not controlled at all.

Section 28: lack of knowledge

Section 28 applies to offences under sections 4(2), 4(3), 5(2), 5(3), 6(2) and 9. It is a defence for the accused to prove they neither knew of nor suspected nor had reason to suspect some fact the prosecution has to prove. Under section 28(3), where the prosecution proves the substance was the drug alleged:

  • it is no defence to show they did not know it was that particular drug;
  • it is a defence if they neither believed nor suspected nor had reason to suspect it was a controlled drug at all;
  • it is a defence if they believed it was a controlled drug which, had it been that drug, would have meant no offence (for example, a drug they were lawfully allowed to possess).

In R v Lambert [2001], the House of Lords indicated that the burden on the defendant should be read as an evidential one. CPS guidance treats it that way: once the defendant raises the issue, the prosecution must disprove it.

Section 5(4) defences

For simple possession only, section 5(4) gives two defences: taking possession to prevent another committing an offence and then, as soon as possible, destroying the drug or handing it to a person lawfully entitled to it; or taking possession in order to hand it to such a person, and taking all reasonable steps to do so as soon as possible.

Exam tip: Section 28 does not apply to section 8. The occupier offence already requires that the person "knowingly" permitted or suffered the activity, so knowledge is part of what the prosecution must prove.

Police powers under the Misuse of Drugs Act 1971

Section 23(2): stop and search for drugs

If a constable has reasonable grounds to suspect that a person is in possession of a controlled drug, section 23 allows the constable to:

  1. search that person, and detain them for the purpose of searching them;
  2. search any vehicle or vessel in which the constable suspects the drug may be found, and require the person in control to stop it;
  3. seize and detain anything found that appears to be evidence of an offence under the Act.

The search must follow PACE Code A, including the requirements on reasonable grounds and on giving the person the grounds and other information. The current codes are on the gov.uk PACE codes page.

Section 23(3): warrants

A justice of the peace, satisfied on information on oath, may issue a warrant authorising any constable, at any time or times within one month, to enter premises (by force if need be), search the premises and any persons found there, and seize drugs or documents where there are reasonable grounds to suspect an offence under the Act.

Obstruction and other powers

Intentionally obstructing a person exercising section 23 powers is an offence under section 23(4). Arrest is under section 24 PACE. Because the main drug offences are triable either way, they are indictable offences, so sections 17(1)(b), 18 and 32 PACE are available for entry and search. See the planned guides on section 18 PACE and section 32 PACE.

Psychoactive Substances Act 2016 in brief

The Psychoactive Substances Act 2016 came into force on 26 May 2016. It makes it an offence to produce, supply, offer to supply, possess with intent to supply, import or export a psychoactive substance, and to possess one in a custodial institution. Food, alcohol, nicotine, caffeine, medicines and controlled drugs are excluded. Simple possession outside a custodial institution is not an offence. Supply and production carry up to seven years.

Worked exam scenarios

Scenario 1. DAVIES is stopped in the street and found with a holdall belonging to a friend. Inside are 30 wraps of cocaine. DAVIES says he knew there was "something" in the bag but thought it was cash. What offence, and is there a defence?

DAVIES has possession: he knew he had the bag, and that is enough for possession of its contents. The quantity and wraps support intent to supply. Section 28 is open to him: he must raise evidence that he neither believed nor suspected nor had reason to suspect the contents were a controlled drug. After Lambert, the prosecution must then disprove it, and a jury will weigh how credible his account is.

Scenario 2. KHAN agrees to look after a bag of cannabis for a dealer and hand it back the next day. Is KHAN guilty of possession with intent to supply?

Yes. KHAN possesses the cannabis and intends to return it to the dealer. Following Maginnis, handing drugs back to the person who deposited them so they can use them for their own purposes is a supply.

Scenario 3. An officer smells cannabis from a car and sees the driver push something under the seat. Can the officer search the car under section 23?

The officer needs reasonable grounds to suspect the driver is in possession of a controlled drug. The officer must be able to explain the grounds objectively; the smell combined with the attempt to hide something is the kind of specific, observed fact that can support them. Section 23(2)(b) then allows the officer to require the driver to stop and to search the vehicle, following Code A.

Common exam traps

  • Possession needs knowledge of the item, not of its nature. Ignorance of what it is goes to section 28, not to possession.
  • Mistaking one controlled drug for another is no defence under section 28(3)(a).
  • Supply needs no payment. Sharing or distributing is supply.
  • "Concerned in" covers people at a distance, such as someone running the phone line who never touches the drugs.
  • Section 8 covers cannabis and opium smoking only, not smoking or using other drugs on the premises.
  • Section 23(2) is about persons and vehicles or vessels; entry to premises needs a section 23(3) warrant or a PACE power.
  • Section 5(3) is committed "whether lawfully or not" in possession, so a lawful holder can still commit it.
  • Psychoactive substances: no simple possession offence except in a custodial institution.

Test yourself

Checked against legislation.gov.uk on 30 October 2026, with the CPS drug offences guidance and the Sentencing Council drug guidelines.

  1. Take the free drugs topic quiz and note where possession, control or section 28 decided the answer.
  2. If you are on the detective route, take the NIE drugs quiz as well.
  3. Sit the free diagnostic, then mock 1 in one timed sitting. Our guide to sergeants' exam questions explains how to eliminate the near-miss options.

10 free Sergeants' exam practice questions with answers

Try each one, then open the answer. For a timed experience use the free mock exam.

  1. 1. What are the prescribed alcohol limits for the purposes of ss.3A to 10 of the Road Traffic Act 1988, as they apply in England and Wales?

    1. A. 35 microgrammes per 100 ml of breath, 80 milligrammes per 100 ml of blood, and 107 milligrammes per 100 ml of urine.
    2. B. 50 microgrammes per 100 ml of breath, 100 milligrammes per 100 ml of blood, and 107 milligrammes per 100 ml of urine.
    3. C. 35 microgrammes per 100 ml of breath, 107 milligrammes per 100 ml of blood, and 80 milligrammes per 100 ml of urine.
    4. D. 22 microgrammes per 100 ml of breath, 50 milligrammes per 100 ml of blood, and 67 milligrammes per 100 ml of urine.
    Show answer

    A. 35 microgrammes per 100 ml of breath, 80 milligrammes per 100 ml of blood, and 107 milligrammes per 100 ml of urine.

    Section 11(2) defines 'the prescribed limit' as 35 microgrammes of alcohol in 100 millilitres of breath, 80 milligrammes in 100 millilitres of blood, or 107 milligrammes in 100 millilitres of urine. Regulations may prescribe other proportions, and lower limits apply in Scotland.

    Source: Road Traffic Act 1988, s.11(2)

  2. 2. WOOD is prosecuted for speeding. The only evidence is from a single police officer, who estimated by eye that WOOD was travelling at about 50 mph in a 30 mph zone. Which is correct?

    1. A. WOOD cannot be convicted solely on one witness's opinion evidence of his speed.
    2. B. WOOD can be convicted, because two officers' opinions are required only on motorways.
    3. C. WOOD can be convicted, because police officers are trained and experienced in estimating vehicle speeds.
    4. D. WOOD can be convicted if the officer gives his evidence on oath and is not shaken in cross-examination.
    Show answer

    A. WOOD cannot be convicted solely on one witness's opinion evidence of his speed.

    Section 89(2) of the Road Traffic Regulation Act 1984 provides that a person shall not be convicted of speeding solely on the evidence of one witness to the effect that, in that witness's opinion, the person was driving at a speed exceeding the limit. Corroboration is needed, for example a second witness or a speed-measuring device.

    Source: Road Traffic Regulation Act 1984, s.89(2)

  3. 3. Which of the following is correct regarding the offences of encouraging or assisting crime under Part 2 of the Serious Crime Act 2007?

    1. A. The offence applies only where the anticipated offence is triable on indictment
    2. B. The offence is committed only if the anticipated offence is at least attempted by the person encouraged
    3. C. It can be committed whether or not the offence encouraged or assisted is ever committed
    4. D. The offence is committed only if the person encouraged is aware of the encouragement
    Show answer

    C. It can be committed whether or not the offence encouraged or assisted is ever committed

    Section 49(1) SCA 2007 provides that a person may commit an offence under Part 2 whether or not any offence capable of being encouraged or assisted by his act is committed. The Part 2 offences are inchoate. Liability depends on D's act and state of mind, not on the outcome.

    Source: Serious Crime Act 2007, s.49(1)

  4. 4. IRWIN takes a pedal cycle from outside a library without the owner's consent and rides it home, intending to return it the next day. Which of the following is correct?

    1. A. IRWIN commits the s.12(1) offence of taking a conveyance without authority
    2. B. IRWIN commits the separate summary offence under s.12(5) relating to pedal cycles
    3. C. IRWIN commits theft, because a pedal cycle is not a conveyance
    4. D. IRWIN commits no offence because he intended to return the cycle
    Show answer

    B. IRWIN commits the separate summary offence under s.12(5) relating to pedal cycles

    Section 12(5) of the Theft Act 1968 provides that s.12(1) does not apply to pedal cycles. Instead it creates a separate summary offence of taking a pedal cycle without consent or lawful authority for one's own or another's use, or riding one knowing it has been so taken, punishable by a fine not exceeding level 3. An intention to return the cycle does not matter for this offence, but it does mean there is no theft.

    Source: Theft Act 1968, s.12(5)

  5. 5. DAVIES buys tablets believing them to be amphetamine (Class B). Analysis shows they are MDMA (Class A). He accepts he knew the tablets were a controlled drug of some kind. Which is correct?

    1. A. DAVIES can be convicted of possessing a Class A drug; not knowing which controlled drug it was is no defence.
    2. B. DAVIES can be convicted only of possessing a Class B drug, as the class he believed he had determines the offence.
    3. C. DAVIES should be charged with attempting to possess amphetamine, as that was the drug he intended to buy.
    4. D. DAVIES has a complete defence under s.28, because he did not know or suspect that the tablets were MDMA.
    Show answer

    A. DAVIES can be convicted of possessing a Class A drug; not knowing which controlled drug it was is no defence.

    Section 28(3)(a) states that the accused is not to be acquitted merely because he did not know or suspect that the substance was the particular controlled drug alleged. As DAVIES knew it was a controlled drug and believed it was one he could not lawfully possess, s.28(3)(b) does not help him. He is charged with possessing the drug he actually had.

    Source: Misuse of Drugs Act 1971, s.28(3)

  6. 6. XU agrees with two others to attack a man and gives them a baseball bat. As they approach the man, XU says quietly 'I'm off' and walks away. The others carry on and seriously injure the man with the bat. Which of the following is correct?

    1. A. Withdrawal can never be a defence once a person has given any assistance
    2. B. XU has a complete defence, because he left before any blow was struck
    3. C. Whether XU effectively withdrew is a question of fact and degree for the jury
    4. D. XU is liable only if he was physically present when the injuries were inflicted
    Show answer

    C. Whether XU effectively withdrew is a question of fact and degree for the jury

    A secondary party is not liable if he withdraws from the joint venture before the offence is committed. Whether he has withdrawn is a question of fact and degree for the jury. Relevant factors include the nature of the assistance given (here, supplying the weapon), how imminent the attack was, and how the withdrawal was communicated (R v O'Flaherty [2004]). A quiet remark as the attack is about to start may not be enough.

    Source: CPS Secondary liability guidance (withdrawal)

  7. 7. Neighbours report constant drug-related visitors, noise and fights at a house. Who may issue a closure notice under s.76 of the Anti-social Behaviour, Crime and Policing Act 2014?

    1. A. A police officer of inspector rank or above, or the local authority.
    2. B. Only a police officer of at least the rank of chief inspector, or the chief executive of the local authority.
    3. C. Only a magistrates' court, on a complaint made by a constable and supported by evidence of nuisance.
    4. D. Any police sergeant, if the premises are residential and the local authority has been consulted.
    Show answer

    A. A police officer of inspector rank or above, or the local authority.

    Section 76(1) allows a closure notice to be issued by a police officer of at least the rank of inspector, the local authority or, since 26 October 2026 (Crime and Policing Act 2026), a registered social housing provider, which may act only for premises it owns or manages (s.76(1A)). The issuer must be satisfied on reasonable grounds that use of the premises has resulted, or is likely soon to result, in nuisance to the public, or in disorder near the premises associated with their use. The notice must be necessary to prevent this.

    Source: Anti-social Behaviour, Crime and Policing Act 2014, s.76

  8. 8. HARRIS, a bar worker, sells a pint of lager to a customer who is 17. HARRIS says he thought the customer looked about 20, but he did not ask for identification. Which is correct regarding s.146 of the Licensing Act 2003?

    1. A. HARRIS has a complete defence, because he genuinely and honestly believed the customer was about 20, even though he did not ask for proof of age.
    2. B. HARRIS commits no offence, because lager is beer and the s.146 offence applies only to wines and spirits.
    3. C. He has a defence only if he believed the buyer was 18+ and took all reasonable steps, or nobody could reasonably have suspected otherwise.
    4. D. HARRIS commits no offence, because only the premises licence holder or the designated premises supervisor can commit it.
    Show answer

    C. He has a defence only if he believed the buyer was 18+ and took all reasonable steps, or nobody could reasonably have suspected otherwise.

    Section 146(1) makes it an offence to sell alcohol to an individual aged under 18. Under s.146(4), the seller has a defence if he believed the individual was 18 or over and either took all reasonable steps to establish age, or nobody could reasonably have suspected from the individual's appearance that they were under 18. Reasonable steps means asking for evidence of age that would convince a reasonable person (s.146(5)).

    Source: Licensing Act 2003, s.146

  9. 9. Which of the following is correct regarding the offence of strangulation under s.75A(1)(a) Serious Crime Act 2015?

    1. A. It requires an intentional act of strangulation, but no injury of any kind need be proved
    2. B. It may be committed recklessly, in the same way as a battery or common assault
    3. C. It requires proof that the victim's breathing or blood circulation was impeded
    4. D. It requires proof that the victim suffered at least actual bodily harm
    Show answer

    A. It requires an intentional act of strangulation, but no injury of any kind need be proved

    Section 75A(1)(a) is committed where A intentionally strangles B. The CPS guidance states that strangulation does not require any particular level of force, any injury, or proof of a consequence such as impeded breathing. It requires an intentional act and cannot be committed recklessly. Suffocation under s.75A(1)(b) is the limb that can be committed recklessly, through a battery.

    Source: Serious Crime Act 2015, s.75A; CPS Strangulation and suffocation guidance

  10. 10. What is the maximum penalty on indictment for aggravated vehicle-taking under s.12A of the Theft Act 1968?

    1. A. Five years, or life imprisonment if a death is caused
    2. B. Six months, as the offence is triable only summarily
    3. C. Two years, or 14 years where an accident caused a death
    4. D. Ten years, whatever the consequences of the driving
    Show answer

    C. Two years, or 14 years where an accident caused a death

    Section 12A(4) of the Theft Act 1968 sets a maximum of two years on indictment. Where it is proved that, in circumstances within s.12A(2)(b), the accident caused the death of the person concerned, the maximum rises to 14 years.

    Source: Theft Act 1968, s.12A(4)

Frequently asked questions

+What are the drug classes in the UK?

The Misuse of Drugs Act 1971 sorts controlled drugs into Class A (for example heroin, cocaine, MDMA and LSD), Class B (for example cannabis, amphetamine and ketamine) and Class C (for example benzodiazepines, anabolic steroids and nitrous oxide). The class sets the maximum penalty. Schedule 2 to the Act holds the full list.

+What is the maximum sentence for possession with intent to supply?

Under Schedule 4, possession with intent to supply a Class A drug carries life imprisonment, and Class B or Class C carries 14 years. The offence is triable either way, except that a possible third Class A trafficking conviction (with a seven-year minimum) makes it indictable only.

+What does section 23 of the Misuse of Drugs Act allow police to do?

If a constable has reasonable grounds to suspect a person is in possession of a controlled drug, section 23(2) lets them search and detain that person, search any vehicle or vessel where the drug may be found (and require it to stop), and seize evidence of an offence under the Act. Section 23(3) lets a justice of the peace issue a search warrant for premises.

+What is the section 28 defence?

Section 28 gives a defence where the accused neither knew of nor suspected nor had reason to suspect a fact the prosecution must prove, such as that they possessed the item. Mistaking one controlled drug for another is no defence, but believing the substance was not a controlled drug at all can be. It applies to possession, intent to supply, supply, production, cultivation and opium offences, not to section 8.

+Is it supply if you buy drugs for a friend?

Technically it can be. Supply includes distributing and does not need payment. CPS guidance notes the courts have said that where two people buy drugs together for their own use, the one who hands over the other's share is likely to be dealt with as for simple possession.

+Is possession of a psychoactive substance illegal?

Simple possession of a psychoactive substance is not an offence, except in a custodial institution such as a prison. Producing, supplying, offering to supply, possessing with intent to supply, importing and exporting are offences under the Psychoactive Substances Act 2016, with a maximum of seven years for supply and production.

+What is the penalty for possession of cannabis?

Cannabis is Class B, so possession carries up to five years' imprisonment on indictment. In practice, gov.uk notes that police may give a cannabis warning or an on-the-spot fine of up to £90 for a first small amount, with escalating responses for repeat possession.

Revision aid, not legal advice. The College of Policing exams follow the 2027 Blackstone's Police Manuals, so check every point against your manual and the current law on legislation.gov.uk. Police Sergeant Exam is independent and not affiliated with the College of Policing, the Home Office or Oxford University Press.

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