The fundamental principles governing criminal law administration may briefly be summarised as follows:—
(1) An ‘act’ in order to become a crime must be committed with criminal intent which is legally termed as mens rea. This principle is contained in the well known Latin maxim, ‘actus non facit ream nisi mens sit rea’. It is to be noted that mens rea or criminal intent consists in doing some act voluntarily with the knowledge that it is fraudulent, dishonest or injurious to another.
However, an act done under a bona fide belief, though criminal, shall be a good defence. Thus, no act shall be a crime without mens rea or guilty mind of the doer. It must be stated that the mens rea in case of a murder consists in malice forethought, for rape in forcible connection with a woman without her consent, for theft in an intention to steal and for procuring stolen goods with the knowledge that the goods was a stolen one. The cases of D.P.P. v. Smith; Shaw v. D.P.P., State v. Dr. Vimladevi, can be cited in support of this connection.
It must be noted that the juristic concept ‘actus reus’ represents the physical aspect of crime while mens rea, its mental aspect. The concept of mens rea comprises several other states of mind, namely, will, intention, motive and so on. Thus, it covers a wide range of mental attitudes and conditions the existence of which would give rise to actus Reus. Sometimes mens rea refers to foresight of the consequences of an act and at others it consists in the act per se irrespective of its consequences.
In some cases mens rea also denotes inattention of the doer of the criminal act which can otherwise be called his recklessness. Thus, in case of manslaughter by negligence, the accused cause’s death of the victim due to his negligence, nevertheless, he is held criminally liable.
Though mens rea is an essential ingredient of every offence, it can be dispensed with in the following exceptional cases:—
(i) Cases not criminal in any real sense but for punishment in view of the public welfare.
(ii) Public nuisance.
(iii) Cases which are criminal in form but for which summary mode of enforcement shall be adequate in view of the urgency and importance of the protection of civil rights violated thereby. Thus, a legitimate exercise of the right of private defence may exclude many intentional acts which would otherwise be offences.
Again, a delicate surgical operation being the only remedy to save the life of a patient, if done with this object but with full knowledge that it can also be fatal, would not be an offence because the intention of the operating surgeon is to save the life of the patient.
(2) Another important principle of criminal law is embodied in the maxim “ignorantia facit excusat, ignorantia juris non excusat”. It suggests that mistake of fact is a good defence in law of crime but not the mistake of law. Thus, a man before going to Church left his gun unloaded. After he left, another man used it for a shoot and thereafter kept it loaded.
On return of the first man from the Church, still thinking the gun to be unloaded as he left it, pulled the trigger with the result his wife was shot dead. The Court held that he was not liable for murder under an excuse of mistake of fact. But there are certain statutory absolute liability cases which afford no excuse to the accused for his ignorance of fact.
Thus, in R. v. Prince, the accused took an unmarried girl under the age of sixteen years out of the possession, and against the will of her father. The defence of the accused that he bona fide and honestly believed that the girl was older than sixteen as appeared from her physical built, was not accepted as the taking of the girl was unlawful. In such cases the law imposes a strict duty and holds the offender liable under criminal law. If a man trespasses on someone’s land thinking that land to be his own, he shall nevertheless be liable.
As regards mistake of law, the criminal law affords no defence but it is a good evidence of mental condition of the offender. The reason for non-admissibility of mistake of law as a defence is that if it were so, everyone would plead it and criminal law administration would be reduced to a sheer farce.
(3) The law of crimes does not permit ex post facto legislation. That is to say, all those acts which may lead to punishment shall be duly notified and no one can be punished for an act which is not listed as crime at the time of its commission, but has become so subsequently.
(4) Another important principle of criminal law is that everyone shall be presumed innocent unless his guilt is specifically proved within the provisions of law. This is intended to afford every possible opportunity to the accused to defend himself.
(5) Under the criminal law an accomplice is treated at par with the principal accused and is punished equally.
(6) There are certain rights and protections afforded to the accused person not only during trial but also before and after trial. They and protections aim at providing a fair trial to an accused and eliminate possible abuse of judicial process resulting into miscarriage of justice. They include right to be produced before the Magistrate, right to bail, release on bond, right to counsel and legal aid etc.
The safeguards extended to an accused in course of trial are protection against self-incrimination and double jeopardy. The former suggests that no person accused of any offence shall be compelled to be a witness against himself while the latter makes it clear that no person shall be punished twice for the same offence. This is expressed in the well known latin maxim nemo debet bis vexari si constat curiae quod sit pro una et eadem causa.
Modern legislation on criminal law permits sufficient discretion to judicial authorities to meet the exigencies of time thus making the law more elastic and adaptable. Likewise, there has been a tendency to substitute indeterminate sentence for determinate one through correctional methods such as probation, parole, reformatories, open air camps, etc.
Justifying this approach Prof. Void observes: “it is not the humanity within the criminal but the criminality within the human being, that needs to be crushed, the wrongdoer must be given a chance to improve”. Dr. Freud, however, suggests that law in fact is one of the agencies of social control, the efficient enforcement of which entirely rests with the institutions such as the police, prosecutors, courts, judges, jurors, probation officers, etc. It is for this reason that effectiveness of criminal law cannot be accurately assessed.