Analysis Of Diminished Capacity And Intoxication Defences
I. OVERVIEW OF DIMINISHED CAPACITY AND INTOXICATION DEFENCES
1. Diminished Capacity (Mental Disorder Affecting Criminal Responsibility)
Often overlaps with NCRMD (Not Criminally Responsible on account of Mental Disorder) under s.16 Criminal Code.
Purpose: To establish that the accused lacked the mental capacity to form the mens rea required for the offence.
Key Elements:
Mental disorder or abnormal condition affecting cognitive ability.
Lack of ability to form intent or appreciate consequences.
Result: May lead to reduced charges, mitigated sentences, or acquittal.
2. Intoxication as a Defence
Governed by s.33.1 of the Criminal Code.
Types of Intoxication:
Voluntary Intoxication: Self-induced by alcohol or drugs. Generally not a defence to general intent offences.
Involuntary Intoxication: Forced or unaware consumption; may negate intent.
Key Principles:
Intoxication cannot excuse general intent crimes (e.g., assault).
Can negate specific intent crimes (e.g., murder requiring premeditation).
The defence is assessed based on whether the accused could form the required mens rea.
II. CASE LAW ANALYSIS
1. R. v. Daviault (1994, SCC)
Issue: Extreme intoxication as a defence for general intent crimes.
Facts
Daviault, extremely intoxicated, committed sexual assault. He claimed he was too impaired to form intent.
Decision
SCC ruled that extreme intoxication (akin to automatism) can, in rare cases, negate general intent if it amounts to non-self-induced incapacity.
Introduced the concept of “extreme intoxication akin to automatism”.
The court limited application to exceptional circumstances to prevent abuse.
Significance
Recognized the rare possibility that voluntary intoxication could negate general intent if it leads to extreme mental incapacity.
Later partially modified by s.33.1, limiting applicability for violent offences.
2. R. v. Daviault Reforms – s.33.1 Criminal Code (1995)
Following Daviault, Parliament enacted s.33.1 to prevent intoxication from being used as a defence to violent general intent offences.
Confirms:
Voluntary intoxication cannot excuse violent acts.
Involuntary intoxication may still be considered.
3. R. v. Parks (1992, SCC)
Issue: Automatism vs diminished capacity.
Facts
Parks, sleepwalking, killed his in-laws. Defence claimed automatism.
Decision
SCC ruled that sleepwalking causing involuntary actions can be a complete defence (non-insane automatism).
Distinguished from mental disorder defences (NCRMD), which require psychiatric evaluation.
Significance
Demonstrates overlap between diminished capacity, automatism, and lack of mens rea.
Highlights that involuntary actions can negate criminal liability.
4. R. v. Stone (1999, SCC)
Issue: Diminished capacity through provocation and intoxication.
Facts
Stone killed his spouse after prolonged provocation and intoxication. He argued he could not form intent due to dissociation and intoxication.
Decision
SCC clarified:
Intoxication can negate specific intent, but not general intent crimes.
Internal factors (mental disorder, provocation) → assessed under NCRMD/diminished capacity framework.
External factors (forced intoxication) → may negate intent entirely.
Significance
Reinforces principle that mens rea is central, and intoxication/diminished capacity must be assessed in context.
Courts distinguish internal vs external causes for incapacity.
5. R. v. Daviault Reconsidered – R. v. Brown (2003, SCC)
Issue: Limits of intoxication defence in sexual assault.
Facts
Brown claimed extreme intoxication prevented him from forming specific intent for sexual assault.
Decision
SCC emphasized that s.33.1 overrides extreme intoxication claims for violent offences.
Voluntary intoxication is generally not a defence for sexual assault or murder.
Courts maintain strict interpretation to protect victims.
Significance
Limits scope of intoxication defence in violent crimes.
Clarifies statutory hierarchy over common-law principles in criminal responsibility.
6. Additional Notable Cases
R. v. Chaulk (1990, SCC) – Diminished capacity through mental disorder; inability to appreciate wrongfulness.
R. v. Daviault (1994, SCC) – Extreme intoxication as automatism-like defence.
R. v. J.W.H. (1999, SCC) – Specific intent crimes vs general intent; intoxication may negate specific intent.
R. v. Parks (1992, SCC) – Sleepwalking as non-insane automatism negating mens rea.
R. v. Stone (1999, SCC) – Internal factors (mental disorder, provocation) affecting capacity to form intent.
III. PRINCIPLES OF JUDICIAL INTERPRETATION
| Principle | Case Example |
|---|---|
| Diminished capacity can negate mens rea | Chaulk, Stone |
| Extreme intoxication may negate specific intent | Daviault (1994) |
| Voluntary intoxication cannot excuse violent general intent offences | s.33.1, Brown |
| Involuntary intoxication may provide complete defence | Daviault, Parks |
| Internal causes (mental disorder, provocation) → NCRMD or reduced liability | Stone, Chaulk |
| Mens rea is central to criminal responsibility | All cases |
IV. CONCLUSION
Diminished capacity and intoxication defences highlight how criminal law balances personal responsibility and incapacity:
Mens rea must be present; if incapacity negates it, criminal liability may be reduced or excused.
Voluntary intoxication is limited in applicability, especially for violent or general intent offences.
Involuntary intoxication or mental disorder may justify complete acquittal or NCRMD findings.
Courts carefully distinguish between internal vs external causes, and general vs specific intent offences.
Key takeaway:
Mens rea is the linchpin of criminal liability, and both diminished capacity and intoxication defences are evaluated in terms of ability to form intent or appreciate wrongdoing.
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