Odger's English Common Law

120 THE ELEMENTS OF A CRIME.
the mind is actively in fault, but also where the mind is as it
were passively to blame, e.g., for recklessness, heedlessness
or want of due caution. The criminality consists in wilfully
or negligently incurring the risk of causing loss or suffering
to others. In the preceding pages of this chapter we have
spoken only of the wilful commission of a criminal act. In
such a case there is only one question which can arise as to
the attitude of the actor's mind, namely, Did he or did he not
intend to do that act ? But it is often also a crime to omit
to do a certain act ; and in connection with such criminal
omission the term mens rea takes a wider and a twofold
meaning.
It may be that the prisoner deliberately resolved not to do
an act which the law required him to do ; if so, he intended
to do that which by the law of the land was criminal, and
such an intention is mens rea.
If, however, the omission was not deliberate, but the result
only of some blunder, or of some inattention or heedlessness,
or of sheer inability to do the act, he may be free from the
imputation of mens rea. Hence nice questions arise as to
the degree of heedlessness or negligence which will be
regarded in our law courts as criminal. An amount of
negligence which would entitle an injured plaintiff to
damages in a civil action will often be insufficient to render
the defendant criminally liable. On the other hand, utter
indifference to the consequences of an act prima facie criminal,
and recklessness as to whether such consequences may or may
not follow, clearly indicate a guilty mind.
Thus it has been held that merely suffering trees to grow so as to obstruct
a highway is not a " wilful obstruction " within section 72 of the Highway
Act, 1835. 1
Again, under an old statute 2 any person who wilfully threw any soil or
rubbish into any part of a certain viver rendered himself liable to a fine.
But where a tanner in the course of his business discharged his refuse into
the river as he had done for years past, it was held that he was wrongly
convicted. " The refuse was not ' wilfully ' thrown in within the meaning
of the clause : for it was discharged in the course of carrying on a lawful
i 5 & 6 Will. IV. c. 60 ; Walker v. Horner (1875), 1 Q. B. D. i.
2 14 Geo. Ill, c. 96.