Welcome to the World of General Defences!
In Criminal Law, proving that someone did a "bad thing" (the Actus Reus) with a "guilty mind" (the Mens Rea) is usually enough to convict them. But sometimes, there is a very good reason why the person acted the way they did. These are called General Defences.
Think of a defence as a "shield." Even if the prosecution proves their case, if the defendant (the person on trial) can raise a successful shield, they might be found not guilty (acquitted) or receive a lesser charge. We are going to look at why the law sometimes says, "You did it, but we won't punish you for it."
1. Self-Defence
This is probably the defence you’ve heard of most. It’s the idea that you can use force to protect yourself, someone else, or even your property.
How it Works (The Two-Step Test)
For this shield to work, the jury has to ask two simple questions:
- Was the use of force necessary? (The Subjective Part): Did the defendant honestly believe they needed to use force? Even if they were mistaken, as long as it was a genuine mistake, the law allows it.
- Was the force used reasonable? (The Objective Part): This is the "Goldilocks" rule. The force shouldn't be too much or too little—it must be "just right" for the situation. You can't bring a chainsaw to a pillow fight!
Quick Review: The law doesn't expect you to "weigh to a nicety" (calculate perfectly) exactly how much force to use in the heat of the moment, but you cannot use force as a way of getting revenge after the danger has passed.
Memory Aid: Just remember N.R. — Necessary and Reasonable.
Key Takeaway: Self-defence is a complete defence. If successful, the defendant is found not guilty.
2. Duress by Threats
Imagine someone holding a gun to your head and saying, "Rob that shop, or I’ll pull the trigger." This is Duress by Threats. You are committing a crime, but only because you are being forced to.
The Rules for Duress
- The Threat: It must be a threat of death or serious injury. A threat to steal your lunch money or reveal a secret isn't enough!
- Who is threatened? It can be the defendant, their immediate family, or someone they feel responsible for.
- The "Reasonable Person" Test: Would a sober person of "reasonable firmness" (someone with average courage) have done the same thing?
- No Escape: If you had a chance to call the police or run away safely, the defence will fail.
Common Mistake to Avoid: You cannot use Duress as a defence for Murder or Attempted Murder. The law says you cannot choose to take another person's life to save your own.
Key Takeaway: Duress is a "concession to human frailty." It recognizes that most people would break the law if their life were truly on the line.
3. Duress of Circumstances and Necessity
Sometimes, it’s not a person threatening you, but a situation. This is Duress of Circumstances.
The Difference
Duress of Circumstances: You commit a crime to avoid a physical threat from the environment.
Example: You are being chased by a gang in a car, so you drive 100mph through a red light to escape. You broke driving laws, but the circumstances forced you to.
Necessity: This is the "lesser of two evils." You choose to break the law to prevent a much worse thing from happening.
Example: This is very rare in English law. A famous example is the case of Re A (Conjoined Twins), where doctors had to perform an operation that would kill one twin to save the life of the other.
Did you know? For a long time, English judges didn't want to allow "Necessity" because they were worried people would just make up excuses for any crime. Today, it is only allowed in very specific, life-and-death medical or emergency situations.
Key Takeaway: These defences focus on why you did it. If the harm you prevented was much bigger than the law you broke, the defence might apply.
4. Consent
Consent means the "victim" agreed to what happened. However, in Criminal Law, you can't just agree to anything!
When does Consent work?
Consent is usually only a defence to Common Assault (like a slight push or a threat) or Battery (a touch). If you cause Actual Bodily Harm (ABH) or worse, consent is usually not a defence.
The Exceptions (The "Public Interest" List)
The law allows consent for more serious harm in specific categories because they are useful to society or part of normal life:
- Properly conducted sports: If you get tackled in rugby and break a rib, you consented to the risk of the game. (But if someone punches you in the face after the whistle blows, that’s different!)
- Medical treatment: You consent to a surgeon cutting you open because it’s for your health.
- Tattooing and Piercing: These are legally "allowed" harms.
- Horseplay: Friendly, accidental roughhousing between friends (see the case of R v Jones).
Case Connection: In the famous case of R v Brown, the court decided that people could not consent to being hurt for sexual pleasure (sadomasochism) because it was not in the "public interest."
Don't worry if this seems tricky... The main thing to remember is that you cannot consent to being seriously injured or killed unless it fits into one of the special "legal" boxes like sport or surgery.
Key Takeaway: Consent must be informed (the person knows what they are agreeing to) and genuine (they weren't tricked or forced).
Quick Review Table
Use this to check your understanding before moving on!
| Defence | Key Concept | Main Limitation |
|---|---|---|
| Self-Defence | Protecting self/property. | Force must be reasonable. |
| Duress (Threats) | "Do it or else." | Not a defence for murder. |
| Consent | Victim agreed. | Usually only works for minor injuries. |