History of Mens Rea and the Evolution of the Concept of Criminal Responsibility

• Author: Richard D. Schneider
• Pages: 249-261

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CHAPTER 13

History of Mens Rea and the Evolution

of the Concept of Criminal Responsibility

Richard D. Schneider

Actus non facit reum nisi mens sit rea.

“An act does not make a person guilty of a crime unless that person’s mind be also guilty.”

— Sir Edward Coke, Beverley’s Case (1603), 4 Co. Rep. 123, 117 E.R. 1118.

I. INTRODUCTION

e British system of criminal justice, from which much of Canadian and American criminal law is

derived, is based on the presumption that an individual is responsible for his acts or omissions and will

be punished for breaking the law. Furthermore, every individual is presumed to know the law and ignor-

ance of the law is no excuse for breaking it. Nevertheless, our criminal justice system does excuse those

who are incapable of governing their actions rationally, either as a result of mental disorder (Criminal

Code of Canada, s. 16) or immaturity (Criminal Code, s. 13).

In this chapter we will explore the historical antecedents and evolution of the mental components of

a criminal act: mens rea, or the guilty mind, and then the “insanity” defence to an otherwise criminal

act. Proof of mens rea is one of the constituent elements of a criminal oence; the other is actus reus, or

the guilty act. An accused will wal k free of conviction should the Crown not prove, beyond a reasonable

doubt, the presence of both actus reus and men s rea. Where these two elements have been suciently

proven, an accused may raise the defence of not criminally responsible on account of insanity. e dis-

tinction between these two notions (lack of mens rea versus absent criminal responsibility) will be ex-

plored here.

II. PRINCIPLES GOVERNING THE CRIMINAL LAW

e fundamental premises of criminal liability that form the foundation of our criminal justice system

are grounded in ordinary notions of morality and justice (Law Reform Commission of Canada (LRC),

1986). ree such notions are generally accepted:

• No one can be justly held responsible for breaking a law unless it was in force at the time of the

alleged violation.

• No one can be held responsible for conduct other than her own (or for conduct that she should have

performed but did not).

• No one can be held responsible for mere behaviour (or absence of behaviour) unless it is accompanied

by some kind of personal culpability or fault such as carelessness, recklessness, or wrongful intention.

e rationale for the rst of the above principles is that to convict and punish someone for an act or

omission where no law is in force that makes that act or omission an oence would be unjust, self-con-

tradictory, and pointless. It is unjust because no punishment is deserved, self-contradictory because it