What about the father who drinks too much, and then takes his near naked kids into a blizzard, where they die of exposure? Seems the courts deemed he could avoid intent or criminal responsibility through drink.
That wasn't the reason he got the sentence he did and the two cases are completely different - one involving a murder charge, one involving a charge of criminal neglect causing harm. In the later case, the accused did not plead not guilty due to insanity, but plead guilty.
Criminal neglect causing death has no minimum sentence unless a firearm is involved (which carries a 4 year minimum imprisonment), though in all cases a life sentence remains an option. Due to the fact that this man was Aboriginal and lived on reserve, a recommended sentence came from his community's judging circle. The judging circle recommended a conditional sentence, but due to a recently passed law this recommendation could not be implemented. This new law stipulates that certain offences causing harm must carry a minimum three year prison sentence, and that is what the judge gave him. Keep in mind that the Crown was only seeking five years imprisonment. At least this is my understanding.
The fact is that you or I can read the headlines or the court documents or whatever, but we only get the basic (and often) sensationalized facts. In the case of the man responsible for criminal neglect causing death, I would assume that the judge would know a bit more about the situation than anyone here. I mean, even the judging circle in his own community where this tragedy happened saw reasons for a lighter sentence.
We can't forget that retribution is only one of the many goals of punishment through the legal system. Others include deterence, removal, compensation, rehabilitation, etc. The judge has to take all of these things into consideration before handing down a sentence, which takes a lot more time and a lot more thought than reading a headline on the Sun. Personally, I don't feel the immensity of a tragedy should be measured in years the convict spends in prison.