§ 136 Relevance and Irrelevance of Motives
We have already seen in what way and to what extent a man’s immediate intent is material in a question of liability. As a general rule no act is a sufficient basis of responsibility unless it is done either wilfully or negligently. Intention and negligence are the two alternative formal conditions of penal liability.
We have now to consider the relevance or materiality, not of the immediate, but of the ulterior intent. To what extent does the law take into account the motives of a wrongdoer? To what extent will it inquire not merely what the defendant has done, but why he has done it? To what extent is malice, in the sense of improper motive, an element in legal wrongdoing?
In answer to this question we may say generally (subject however, to very important qualifications) that in law a man’s motives are irrelevant. As a general rule no act otherwise lawful becomes unlawful because done with a bad motive; and conversely no act otherwise unlawful is excused or justified because of the motives of the doer, however good. The law will judge a man by what he does, not by the reasons for which he does it.
“It is certainly,” says Lord Herschell,347 “a general rule of our law that an act prima facie lawful is not unlawful and actionable on account of the motives which dictated it.” So it has been said:348 “No use of property which would be legal if due to a proper motive can become illegal because it is prompted by a motive which is improper or even malicious.” “Much more harm than good,” says Lord Macnaghten,349 “would be done by encouraging or permitting inquiries into motives when the immediate act alleged to have caused the loss for which redress is sought is in itself innocent or neutral in character and one which anybody may do or leave undone without fear of legal consequences. Such an inquisition would I think be intolerable.”
An illustration of this irrelevance of motives is the right of a landowner to do harm to adjoining proprietors in certain defined ways by acts done on his own land. He may intercept the access of light to his neighbour’s windows, or withdraw by means of excavation the support which his land affords to his neighbour’s house, or drain away the water which would otherwise supply his neighbour’s well. His right to do all these things depends in no way on the motive with which he does them. The law cares nothing whether his acts are inspired by an honest desire to improve his own property, or by a malevolent impulse to damage that of others. He may do as he pleases with his own.350
To this rule as to the irrelevance of motives there are, however, very important exceptions, more especially in the criminal law. The chief of these are the following.