Can materials disclosed in a civil action be used in a criminal one?
Heather Douglas examines exactly this question in her recent article, “Can Discovery Evidence Be Used in a Criminal Case?” on SLAW.
The Division Court in S.C. v N.S., 2017 ONSC 5566 said that it was entirely up to the trial judge:
 […] this plain reading of the Rule does not mean that the appellant has a carte blanche to use the Discovery Evidence as he wishes. The trial judge in the criminal prosecution will determine if the use of the Discovery Evidence is proper in accordance with the rules that apply to all evidence. Trial judges always have a gatekeeping role regarding evidence that is proffered at a trial. Trial judges must determine if the evidence is properly admissible tested against well-established factors, including whether the evidence is relevant and whether its probative value outweighs any prejudicial effect: Shearing at para. 107.”
Douglas notes her concern “about its implications for civil matters. Civil matters are already experiencing delays. … This ruling may incentivize civil counsel to delay routine documentary disclosure to the conclusion of the criminal matter, further delaying already languishing cases.”