By laying too many charges the prosecution may give the accused a get-out-of-jail-free card.
This happened in R v JF  SCC 60 (31 October 2008).
There was one death in this case, but the accused faced two charges of manslaughter. The jury convicted on the more serious, and acquitted on the lesser; this led the SCC to quash the conviction because the verdicts were inconsistent. The accused was left with two acquittals.
The accused's foster child had died as a result of injuries sustained at the hands of the accused's wife, who pleaded guilty to manslaughter. The two charges brought against the accused were
- Manslaughter by criminal negligence;
- Manslaughter by failure to provide the necessaries of life.
Deschamps J was the sole dissenting judge. She was able to perceive a distinction between the elements of the charges that provided a basis for the different verdicts. This distinction is the kind of thing that (in my view) you can persuade yourself you can see if you don't look directly at it, but as soon as you do it seems insubstantial. The jury may have had a reasonable doubt on the second charge, she reasoned, because they did not accept the Crown had proved an element peculiar to it, namely that the accused's failure had the effect of endangering V's life or of causing permanent endangerment to his health.
Deschamps J's judgment illustrates how a complicated explanation is unlikely to be convincing. Look at paras 73 and 74. Given that the jury concluded that the Crown had not proved that the accused's failure to provide the necessaries of life had endangered V's life, or caused or likely caused his health to be endangered permanently, how could the jury then conclude that on manslaughter by criminal negligence his marked and substantial departure from what a reasonable parent would do in the circumstances caused V's death?
On the first charge, the jury found (and correctly so in Deschamps J's opinion) that the accused should have been alert to the risk to V's safety.
Fish J delivered the judgment of himself, McLachlin CJ, Binnie, Abella, Charron and Rothstein JJ. The verdicts were inconsistent because each charge required proof that the accused had failed in his duty to protect V. The real distinction between the charges was, as Fish J said at 11, that in the present context the criminal negligence charge requires a marked and substantial departure from the conduct of a reasonably prudent parent, whereas the other charge simply requires a marked departure.
The second charge had the lesser degree of fault, and acquittal on it meant that the jury could not have found proved the higher degree of fault in the first charge. The jury should have considered the first charge only if it found the second proved.
Juries may well be more pragmatic that the law permits. There is a niggling possibility here that the jury simply thought that there should be one conviction, which should be for the more serious charge.
The Crown should have put its case to the jury in the way indicated by Fish J: first consider the charge of manslaughter by failure to provide the necessaries of life. If the verdict on that is guilty, then consider the charge of manslaughter by criminal negligence. If the verdict on the failure to provide the necessaries charge is not guilty, then the verdict on the criminal negligence charge must also be not guilty. Since it did not do this, the Crown lost on both.
The law appears to be different in New Zealand, where the charges would both require the same "major departure" from the standard of care expected of a reasonable person: s 150A, 160(2)(a) and (b) Crimes Act 1961 and R v Powell  1 NZLR 666 (CA), so they could not be put in the way indicated in R v JF. In such a case it would be necessary to make clear what the difference between the charges was alleged to be, otherwise only one could be left to the jury.