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Criminal Defences for SQE1

Part of our SQE1 Criminal Law guide → View the full SQE1 Criminal Law guide

11 Apr 2026

Criminal defences can result in a complete acquittal, partial reduction in charge, or special verdict. SQE1 tests your knowledge of requirements and circumstances of availability.

Criminal Defences

Criminal Law > Criminal Defences

What Are Criminal Defences?

Candidates often miss easy marks on SQE1 by failing to recognise that the same defence may not be available across all offences — duress doesn't work for murder, and intoxication's effect depends on whether the offence is basic or specific intent. A criminal defence is a legal basis on which a defendant denies or reduces criminal liability. Defences may be complete (resulting in acquittal, such as self-defence or duress) or partial (reducing the offence, such as diminished responsibility or loss of control reducing murder to manslaughter). Some defences negate mens rea (such as intoxication in certain circumstances), while others justify or excuse the defendant's conduct.

The burden of proof generally remains on the prosecution to disprove the defence once the defendant raises it, with the notable exception of insanity and diminished responsibility, where the burden shifts to the defendant on the balance of probabilities.

Each defence interacts with the actus reus and mens rea requirements in different ways.

Key Principles for SQE1

  • Self-defence / defence of another (common law and Criminal Law Act 1967, s.3): The defendant must honestly believe that the use of force is necessary, and the degree of force must be reasonable in the circumstances as the defendant believed them to be. A person may use pre-emptive force. The defendant is judged on the facts as they honestly believed them — even if that belief is mistaken, provided it is genuinely held (but not if the mistake is caused by voluntary intoxication). For a detailed treatment of how defences interact with the broader structure of Criminal Law, consult the complete guide.

  • Duress by threats: The defendant committed the offence because they were threatened with death or serious physical injury to themselves or another, a reasonable person of similar characteristics would have responded in the same way, and the defendant had no reasonable opportunity to escape the threat. Duress is not available as a defence to murder or attempted murder.

  • Duress of circumstances: Arises where external circumstances (not a direct threat from a person) compel the defendant to commit the offence to avoid death or serious injury. The same limitations apply — not available for murder or attempted murder.

  • Necessity: A rarely successful defence where the defendant argues that committing the offence was necessary to prevent a greater evil. Recognised in limited situations. Its scope remains uncertain and it is not available for murder.

  • Intoxication — voluntary: Not a defence to basic intent offences (where recklessness suffices as mens rea). May negate the mens rea for specific intent offences (where nothing less than intention will suffice), potentially reducing the charge (e.g., from murder to manslaughter).

  • Intoxication — involuntary: If the defendant was involuntarily intoxicated (e.g., drink spiked) and lacked the mens rea for the offence, this provides a complete defence to both basic and specific intent offences. However, involuntary intoxication is no defence if the defendant still formed the required mens rea despite the intoxication.

  • Insanity (M'Naghten Rules [1843]): At the time of the offence, the defendant was labouring under a defect of reason, caused by a disease of the mind, such that they did not know the nature and quality of their act, or did not know that what they were doing was legally wrong. The burden is on the defendant (balance of probabilities). The verdict is 'not guilty by reason of insanity.'

  • Automatism: A complete defence where the defendant's actions were involuntary due to an external cause (not a disease of the mind). Examples include a blow to the head, a swarm of bees, or the effect of prescribed medication taken properly. If caused by an internal factor (e.g., epilepsy, diabetes-related hypoglycaemia from insulin), it is classified as insane automatism, not simple automatism.

  • Consent: A defence to common assault and battery. Generally not available for offences causing ABH or above, subject to recognised exceptions (properly conducted sport, reasonable surgery, tattooing, horseplay).

Exam tip

When you see a scenario asking about a defence, work through a checklist: (1) Is it duress? If yes, is it a murder charge? (murder = not available). (2) Is intoxication relevant? If yes, is it a basic or specific intent offence? (3) Is self-defence raised? The force must be reasonable in the circumstances as the defendant believed them. This systematic approach prevents common errors.

How This Appears in SQE1 Questions

SQE1 questions present a scenario and ask which defence, if any, is available. This is a classic SQE1 trap: examiners present facts that appear to raise a defence but then reveal that the defence is not available for the specific offence charged. Key traps include:

  • Applying duress to a murder charge (not available)
  • Treating voluntary intoxication as a defence to a basic intent offence (it is not)
  • Confusing insane automatism (internal cause — leads to a special verdict) with non-insane automatism (external cause — leads to acquittal)

Questions on self-defence often test whether the force was reasonable in the circumstances as the defendant believed them to be, even if that belief was mistaken.

Common Mistakes Students Make

  • Applying duress to murder or attempted murder — it is not available for either
  • Treating voluntary intoxication as a defence to basic intent offences — it is only relevant to specific intent offences
  • Confusing insane automatism (internal cause — disease of the mind) with non-insane automatism (external cause) — the classification determines the verdict
  • Forgetting that self-defence is judged on the facts as the defendant honestly believed them — even if the belief was mistaken (provided the mistake was not caused by voluntary intoxication)

Quick Summary

  • Self-defence: honest belief in necessity, reasonable force in circumstances as believed.
  • Duress: threat of death/GBH, would reasonable person respond similarly, no reasonable opportunity to escape.
  • Not available for murder.
  • Intoxication: voluntary = no defence to basic intent, may negate mens rea for specific intent.
  • Insanity: defect of reason from disease of mind.
  • Automatism: involuntary conduct from external cause.

Want to test this now? Try a few SQE1-style questions below before moving on.

Test Yourself

Test yourself

Quick check questions based on this article.

Question 1

Scenario

A young man works as a delivery driver for a logistics company. His manager, who is known to have connections with organised criminals, tells the young man that he must use his delivery van to transport a sealed package to an address on the other side of the city. The manager tells the young man that if he refuses, the manager will ensure that the young man's family are 'dealt with'. The young man is genuinely terrified. He has witnessed the manager behave violently towards other employees in the past, including one incident where the manager broke an employee's arm for refusing to follow instructions. The young man believes the threat to his family is real and imminent. The young man agrees to transport the package. He drives the van to the specified address and delivers the package. Police subsequently stop the young man on his return journey and discover traces of controlled drugs in the van. The package is later found to have contained a large quantity of cocaine. The young man is charged with being concerned in the supply of a controlled drug. He tells his solicitor that he had no idea the package contained drugs but suspected it might contain something illegal. He also tells his solicitor that he could have driven to a police station instead of delivering the package, but he was too frightened to do so because the manager had told him he would know if the delivery was not made. The young man has no previous convictions and no involvement in drug offences.

Is the defence of duress likely to be available to the young man?

Question 2

Scenario

A man is walking home from a pub at approximately 11pm on a Friday evening. He has consumed four pints of lager over the course of three hours. As he turns a corner, he sees a group of three teenagers blocking the pavement. One of the teenagers steps forward and demands the man hand over his wallet and mobile phone. The man refuses. The teenager who made the demand then produces what appears to be a small folding knife. The man, who has some training in martial arts, grabs the teenager's arm and twists it, causing the teenager to drop the knife. The man then punches the teenager once in the face, causing the teenager to fall to the ground. While the teenager is on the ground, the man stamps on the teenager's hand, breaking two of his fingers. The other two teenagers have already run away by the time the man stamps on the teenager's hand. The teenager is taken to hospital and is diagnosed with a fractured nose and two broken fingers. The man tells police he was terrified and acted instinctively throughout the entire incident. The man's blood alcohol level at the time of the incident is estimated at twice the legal driving limit. A witness confirms that the teenager did produce what appeared to be a knife.

Is the man likely to succeed in a defence of self-defence in relation to all of his actions?

Question 3

Scenario

A man is walking past a school playground during break time when he sees an adult man climb over the school fence and grab a child by the arm. The child screams and struggles. The man outside the school rushes through the school gate, runs towards the adult inside the playground, and tackles him to the ground, causing the adult to bruise his elbow and graze his face. It later transpires that the adult was the child's father, who had come to collect his child early and had climbed the fence because the main entrance was locked. The father had lawful parental responsibility. The man who intervened is charged with common assault (battery). The man who intervened does not know the father or the child. He is a retired firefighter with no previous convictions.

Which of the following best describes whether the man can rely on the defence of defence of another?

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