The main characteristics of a crime are as follows:—
(1) External consequences:
Crimes always have a harmful impact on society may it be social, personal, emotional or mental?
(2) An act (Actus Reus):
There should be an act or omission to constitute a crime. Intention or mens-rea alone shall not constitute a crime unless it is followed by some external or overt act. Generally, omitting to do something will not amount to actus Reus of an offence. The criminal law usually punishes individuals for positive conduct and not for inaction. There are, however, some notable exceptions. For example, a police officer may have a duty to act to prevent an assault and if he does not, he will be liable to be punished under the law.
(3) Mens-rea or guilty mind:
Mens-re is one of the essential ingredients of a crime. It may, however, be direct or implied. The implied mens-rea is otherwise termed as constructive mens-rea.
Mens rea implies that there must be a state of mind with respect to an actus Reus, that is, an intention to act in the proscribed fashion. It is, however, important to distinguish mens rea from motive. Thus if a person steals away a few loaves of bread from someone’s kitchen to feed a child who is dying of hunger, the motive here may be honourable and understandable, nevertheless the mens rea being to commit the theft, the person would be convicted for theft.
His motive may, however, be taken into account in sentencing and he may be less severely punished because of his good motive. In short, motive should be taken into consideration at the sentencing stage and not at the time of deciding the question of mens rea.
(4) Prohibited act:
The act should be prohibited or forbidden under the existing penal law. An act, howsoever immoral, shall not be an offence unless it is prohibited by law of the land.
The act in order to constitute a crime should not only be prohibited by the law but should also be punishable by the State. The punishment is usually set out in terms of a maximum and the actual punishment in any particular case is left to the discretion of the judge. Both, the defence and the prosecution have a right to appeal against the quantum of sentence.