The importance of Criminal Law as a vehicle for the advancement of humanity cannot be overemphasized.
“This is the law on which men place their ultimate reliance for protection against all the deepest injuries that human conduct can inflict on individuals and institutions.”1
This, then, is the basis for the definition of offences and the stipulation of corresponding punishments. In attendance with this, is the recognition of certain defences to criminal responsibility.
In order to secure a conviction against an accused person, two basic requirements of criminal liability must be established – first, the physical conduct (actus reus), and second, the state of mind (men’s rea) of the accused person must be legally blameworthy. The defence of mistake falls within the category of defences which is negative mens rea. If due to some
mistaken belief, the accused person is incapable of possessing such a blameworthy state of mind, he should not be held criminally responsible.
It was observed as far back as 1897, that: “… the absence of mens rea really consist in an honest and reasonable belief entertained by the accused of the existence of facts which, if true, would make the act charged against him innocent.”2
1. Wechsler: The challenge of a Model Penal Code.
2. Dank of New South Wales v. Piper  A.C. 383.
The plea of mistake may be raised either alone or with similar defences to criminal responsibility.
Particular attention is observed in homicide cases where the life of the accused is at stake. The Supreme Court in Kuvawa Takida v The State, 3 held that all the defences which are available to an accused person on evidence, should as a matter of course, be considered by the courts, whether or not such defences are raised specifically by the accused or by his counsel.
Organisational Structure of the Thesis
The thesis is divided into seven chapters. Chapter I is the introductory chapter and it contains an account of the historical background and origin of the Penal and Criminal Codes.
The relationship between the two Nigerian codes and their relationship with other Legal systems is also examined. Chapter 11 examines the early period in English Law when mistake came to be one of the early defences recognised, as not being compatible with the existence of mens rea. Thereafter, the development of the defence viz-a-viz the requirement for men’s rea is traced, pointing out the difficulties in the area of mistake of mixed law and fact. The requirements for the plea of mistake are analysed and the critique and public policy behind them are stated.
Chapter III is a detailed study of the application of the defence of mistakes in the Nigerian Codes. The controversial issue of “reasonableness of mistake” is treated at length, pointing out the conflicting viewpoints of experts and the practice of the courts in this regard. The chapter seeks to identify inadequacies and shortcomings in the law and attempts to discover the reasons behind them.
Chapter IV is devoted to an extensive and in-depth analysis of the defence of mistakes based on the supernatural; in the form of witchcraft, juju, ghosts, voodoo and the like.
Particular attention is given to the issue of the reasonableness of the belief, or the action following the belief, in an attempt to discover any hidden motive that may be haboured by the accused person. The merit or otherwise of the notion that the prevalence of the belief in witchcraft is enough evidence for its acceptability is explored. Judicial authorities from several jurisdictions with varying socio-cultural settings are examined, in an attempt to discover any trend in this mysterious and topical phenomenon.
Chapter V is an account, of some related defences to mistake. An attempt is made to highlight the application of common concepts to the defences, and areas of differences are noted. These defences include private defence, insanity, provocation and bona fide claim of right.
Chapter VI is an investigation of the application of the defence of mistake in other jurisdictions, particularly, India and the Sudan. Attention is paid to common grounds with the position in Nigeria, and these are duly specified. Areas of difference are also pointed out.
Chapter VII, the concluding chapter, summarises the thesis and the conclusions drawn therefrom. The researcher’s recommendations and proposals for reform are stated here. These are respectfully submitted with a view to rectifying some of the patent defects now existing in the law.The Defence of Mistake in Nigerian Law