(1) Nothing is an offence which is done by a person who at the time of doing it, by reason of unsoundness of mind, is incapable of knowing the nature of the act or that what he is doing is wrong and contrary to law.
(2) For the purpose of this section, if a person was in a state of intoxication at the time of the act or omission complained of and-
(a) the state of intoxication was such that he did not know that the act or omission was wrong or he did not know what he was doing; and
(b) the state of intoxication was caused without his consent by the malicious act of negligence of another person,
he shall be deemed to be a person of unsound mind.
(3) In this section, "intoxication" shall be deemed to include a state produced by drugs.