Validity of a guilty plea may be affected by failure of Crown to make full disclosure

R. v. Henry, 2011 ONCA 289 deals with striking a guilty plea. The Court held:

[27]         A breach of the duty to disclose can impact on the validity of a guilty plea where it affects the basis upon which the accused decides to plead guilty: Taillefer; Duguay at para. 88. Where non-disclosure is advanced as a basis for a claim that a plea of guilty was uninformed, an accused must demonstrate a reasonable possibility that the undisclosed material would have influenced his or her decision to plead guilty, if it had been provided prior to entry of the plea. In cases of non-disclosure, the question is whether a reasonable and properly informed person, put in the same position, would have run the risk of standing trial had she or he received timely disclosure of the undisclosed information, when it is assessed along with the previously disclosed information: Taillefer; Duguay at para. 90.  In cases of non-disclosure, where there is a realistic possibility that an accused would have run the risk of a trial, had she or he been in possession of the undisclosed information or new avenues of investigation, then the accused should be given leave to withdraw the plea of guilty: Taillefer; Duguay at para. 90.