I have a relative who was an MP when they voted on the death penalty. He explained that, because there were cases of wrongful conviction, and it was very hard to be absolutely certain in every single case that the accused was guilty, he could not support a measure that could result in innocent people being executed.
I understood his position, and while I believe that child molesters should face capital punishment, it's hard to argue with his point.
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Contrary to predictions by death penalty supporters, the homicide rate in Canada did not increase after abolition in 1976. In fact, the Canadian murder rate declined slightly the following year (from 2.8 per 100,000 to 2.7). Over the next 20 years the homicide rate fluctuated (between 2.2 and 2.8 per 100,000), but the general trend was clearly downwards. It reached a 30-year low in 1995 (1.98) -- the fourth consecutive year-to-year decrease and a full one-third lower than in the year before abolition. In 1998, the homicide rate dipped below 1.9 per 100,000, the lowest rate since the 1960s. The overall conviction rate for first-degree murder doubled in the decade following abolition (from under 10% to approximately 20%), suggesting that Canadian juries are more willing to convict for murder now that they are not compelled to make life-and-death decisions.