The state is not permitted to use a constitutional right against you at a criminal trial.
With respect to your right to disclosure, a Crown Attorney is prohibited, as a general rule, from cross-examining you on matters relating to disclosure.
The Crown may cross the line during the cross-examination of an accused with some variation of the following line of questioning:
You obtained a copy of the police investigative file before trial?
You reviewed the statements of the witnesses?
You reviewed the forensic evidence?
Is it not true that you concocted your evidence after you read the police file?
You have tailored your evidence to fit what you have learned from the disclosure materials?
For a member of a jury unfamiliar with the central role of disclosure in the pre-trial process this line of questioning insinuates that the accused has done something improper by accessing the disclosure materials. The Crown is asking the jury to discount the accused's testimony on the sole basis that the accused has exercised a constitutional right in advance of trial.
One of the clearest denouncements of this prohibited line of questioning comes from Justice Doherty, speaking for a unanimous Ontario Court of Appeal:
...As a matter of common sense, there may be considerable force to the suggestion that a person who gets full advance notice of the other side's evidence and testifies last is in a position to tailor his or her evidence to fit the disclosure. That inference, no matter how logical, cannot be drawn without turning fundamental constitutional rights into a trap for accused persons. Where any such suggestion seeps into the cross-examination of an accused, it must be eradicated by the trial judge. (R. v. I.W.,  O.J. No. 258 (C.A.) at paragraph 20, emphasis added)
Defence counsel must be ready to object when a Crown asks an accused about matters relating to disclosure. The default is that such a line of questioning is impermissible and potentially prejudicial to an accused's right to a fair trial.
A trial judge must intervene and compel the Crown to articulate what, if any, case specific factors, above and beyond the mere exercise of the constitutional right, serve to provide legitimacy to the proposed line of questioning.
- A Crown Attorney must anticipate that any questions about matters relating to disclosure will be subject to judicial scrutiny. As stated by Justice Doherty in in R. v. I.W., at paragraph 23:
While questions concerning disclosure are appropriate in some situations, they are always potentially dangerous. I think the prudent course whenever Crown counsel wish to cross-examine on matters relating to disclosure is to vet the proposed line of questioning with the trial judge in the absence of the jury.
- An accused’s testimony about his use of the disclosure materials during examination-in-chief may open the door for cross-examination by the Crown. As stated by Justice Doherty in R. v. I.W., at paragraph 22:
I do not intend to suggest that every line of cross-examination involving reference to disclosure is improper. Sometimes, it will be necessary for the Crown to establish that an accused received disclosure as a step in a legitimate line of cross-examination. For example, the appellant had referred to telephone records of calls between himself and the complainant in the course of his examination-in-chief. He had used those phone calls to assist him in placing the times and dates of certain meetings with the complainant. In cross-examination, Crown counsel brought out the fact that the appellant had full access to those records before he testified. This was proper cross-examination intended to show that the appellant was aware of the contents of the phone records before giving his evidence and that any suggestion that the records confirmed his testimony should be considered in that light.