Severance is based on prejudice

R. v. Robins, 2013 ONCA 65 is a recent source for the principle that severance of charges ought to be based on any prejudice arising from trying matters together:

[2]          The appellant submits that the trial judge erred in failing to sever the weapons offences from the child pornography offences. Whether to grant severance is a discretionary decision. The trial judge made no error in principle and her decision is not unreasonable. There was little, if any, prejudice from the joint trial. There was no suggestion that the appellant used the weapon or that it had anything to do with his use of his computer to make child pornography available. There was little likelihood that the jury would reason from the fact that the appellant was in possession of the gun that he was therefore more likely to have made child pornography available.