Odger's English Common Law

CRIME AND TORT. 45
should claim damages from him ; each plaintiff must show a separate
loss peculiar to himself. Thus, a conspiracy by two or more persons to do
an unlawful act is in itself a crime. In order to sustain an action for such
a conspiracy the plaintiff must not only prove the conspiracy ; he must
also show that some wrongful act was done in pursuance of it by the
defendants which has caused some special or particular damage to himself. 1
It is always, however, a defence to a charge of crime that
the mind of the accused did not go with his act. He must
know what he is doing, and he must know that what he is
doing is wrong. He must possess both will and judgment
and be free to exercise both. Hence no man can commit
a crime when he is asleep or has been thoroughly drugged ;
but drunkenness voluntarily produced is no defence in ordi-
nary cases. No infant under seven years of age can-commit a
crime. Coercion and extreme necessity are defences in all
save the gravest cases. A lunatic will be punished if he
knows both what he is doing and that he ought not to do it,
although his desire to do it may be prompted by some
delusion. But he will not be liable where the delusion is
of such a kind that, if the facts were as he supposed, his act
would be justifiable. So, if a criminal act be committed
under a reasonable mistake as to a matter of fact, the
prisoner's guilt depends on whether he would still be liable
if the facts were as he supposed. A mistake as to the law
excuses no one.
In ordinary cases the burden of proving such facts as som-
nambulism, lunacy, duress and mistake lies on the prisoner.
For the law presumes that every one of full age knows what
he is doing, knows right from wrong, and knows (and there-
fore intends) the natural consequences of his act.
1 See post, pp. 625 et seg.