Knowledge and desire are the two necessary constituents of intention. An act may be intentional, unintentional or partly intentional and partly unintentional.
Intention does not necessarily involve expectation. The consequences desired may not be expected. I may intend a result when I know to be improbable.
Conversely, expectation does not, in itself amount to intention. A surgeon may know well that his patient will die of the operation, yet he intends the recovery and not that his patient should die.
A man doing an act designedly is imputed the desire as to its inevitable consequences though these may not have been present in his mind. Thus, he who causes grievous hurt to another, though with no interest to kill him, is guilty of murder if death ensues.
Immediate and Ulterior Intent:
Intention is divisible into immediate and ulterior intent. A crime is seldom committed for its own sake. There is some ulterior object in the commission of the crime. When a robber robs a person, his immediate intention is to rob the person, but the ultimate or ulterior intent is to purchase food or wine for himself.
He intends the attainment of his ulterior object no less than he intends the wrongful act itself. His intent is clearly twofold, viz., immediate and ulterior, the former relating to the wrongful act while the latter to the object or objects for which the act is done.
The ulterior object is called motive while the immediate act is intention. Motive is a state of mind existing prior to the commission of an act. Thus, the immediate intention may be bad while the ulterior intent may be good, but the act will nonetheless be wrongful. The ulterior intent is the motive of the act.
Motives of Wrongdoer:
As a general rule a man’s motive is irrelevant in determining the question of legal liability. Generally, no act otherwise lawful becomes unlawful because it has been done with a bad motive and conversely an act otherwise unlawful cannot be excused because of the good motives of the doer of the act. To this rule of irrelevance of motives the following form the exceptions:
1. Criminal Attempts: Salmond observes that an attempt to commit an indictable offence is itself a crime and there is no distinction in the eye of law between a crime and an attempt to commit a crime.
The act itself may be perfectly innocent, but is deemed criminal by reason of the purpose with which it is done. To mix arsenic in food is itself a lawful act for the purpose or the object may be to kill rats; but if the purpose is to kill a human being, the act will become a criminal attempt.
There are four stages in the commission of a crime, viz., intention, preparation, attempt and completion. Of these the former two are commonly innocent, but the last two stages in the offence are grounds of legal liability.
2. A second exception is about cases in which a particular intent forms part of the definition of a criminal offence, e.g., in the case of burglary or forgery the motive for the offence is necessary.
3. Then there are the exceptional cases of civil wrong in which motive is material to liability. Generally, civil liability arises independently of motive; but in some cases, as in defamation, libel or malicious prosecution, motive becomes relevant. The plaintiff must prove malice before the defendant can be held responsible for damage.
4. Lastly, in cases of private defense when exercised to defend one’s body or properly against unlawful aggression, it is considered necessary to examine whether the real motive was to save life or to take revenge upon a man already in your clutches.