Defences in Criminal Law NSW: A Comprehensive Guide

1. Statutory Defences

1.1. Self-Defence
Self-defence is one of the most commonly used defences in criminal law. Under Section 418 of the Crimes Act 1900 (NSW), a person may use force to defend themselves or others from an immediate threat of unlawful violence. The force used must be proportional to the threat faced, and it must be necessary for the protection of oneself or others.

• Example: If an individual is attacked and responds with equal or lesser force to prevent harm, they may be justified in using self-defence. However, if the response is excessive or preemptive, the defence may not apply.

1.2. Duress
Duress involves committing a crime under the threat of serious harm or death. According to Section 21 of the Crimes Act 1900 (NSW), duress can be a valid defence if the defendant was forced to commit the offence due to threats of harm from another person. The threat must be immediate, and the defendant must have had no reasonable opportunity to escape or seek help.

• Example: A person who is coerced into committing a robbery by a threat of violence may use duress as a defence, provided the threat was imminent and the crime was committed under duress.

1.3. Necessity
Necessity is a defence used when a defendant commits an offence to prevent a greater harm. This defence, although less commonly used, argues that the unlawful act was the lesser evil in the face of an imminent threat. The defence requires that the harm avoided outweighs the harm caused by the offence.

• Example: If a person breaks into a cabin to escape severe weather conditions, and this act results in property damage, necessity may be argued as the defence since the greater harm (exposure to severe weather) was avoided.

2. Common Law Defences

2.1. Mental Illness
The mental illness defence, also known as the insanity defence, is applicable when a person is unable to understand the nature of their actions due to a severe mental illness. Under common law principles and Section 38 of the Mental Health (Forensic Provisions) Act 1990 (NSW), if a defendant was suffering from a mental illness that impaired their ability to appreciate the criminal nature of their conduct, they may be found not criminally responsible.

• Example: A person who commits a crime while in a psychotic state may be deemed not criminally responsible if it is proven that their mental illness significantly affected their understanding of the act.

2.2. Automatism
Automatism refers to actions taken without conscious control. Under common law, if a person commits an offence while in a state of automatism, such as during a sleepwalking episode, they may be acquitted of the charges. Automatism must be proven to be caused by an external factor, such as a medical condition or a reaction to medication.

• Example: A person who accidentally harms someone while sleepwalking may use automatism as a defence if it can be shown that the sleepwalking episode was an involuntary action.

3. Procedural Defences

3.1. Lack of Evidence
A lack of evidence defence argues that there is insufficient evidence to prove the defendant's guilt beyond a reasonable doubt. In criminal proceedings, the burden of proof lies with the prosecution, and if the evidence presented fails to establish guilt, the defendant may be acquitted.

• Example: If the prosecution cannot provide credible evidence linking the defendant to the crime scene, the defendant may be found not guilty due to lack of evidence.

3.2. Unfair Trial
Unfair trial claims are made when procedural errors or misconduct during the trial process compromise the fairness of the trial. This can include violations of the defendant’s rights, such as improper handling of evidence or prejudicial conduct by the court.

• Example: If key evidence was improperly admitted or if the defendant’s right to a fair hearing was compromised, the conviction may be challenged on the grounds of an unfair trial.

4. Conclusion

Understanding the various defences available in NSW criminal law is crucial for anyone involved in the legal system. Each defence has specific requirements and limitations, and their applicability depends on the circumstances surrounding the case. By comprehending these defences, individuals and legal professionals can better navigate the complexities of criminal law and ensure that justice is served effectively and fairly.