That depends on where you are charged and what the charge is.
If it is a routine DUI sort of case, in most places of Ontario you will be given disclosure on your first court date. The disclosure would include a copy of the court information (the charging document), a summary of the allegations against you, police officer and civilian witness notes, your criminal and highway traffic act record (if any), and other miscellaneous items.
The important case of R. v. Stinchcombe sets out that an accused is entitled to know the case against them. The police and Crown cannot hide evidence and spring it on the accused on the day of trial.
Some areas of the province such as Eastern Ontario, including Belleville, Kingston, Bancroft and others, the Crown will not let you have the disclosure yourself. They will send it to your lawyer for the lawyer to discuss it with you (the lawyer must maintain possession of it), or Duty Counsel can discuss it with you. Obviously this is less convenient to both the client and his or her lawyer.
There are no obvious reasons for why there is not the same disclosure policy throughout Ontario. Local practices vary, and I guess that is the reason for it.
If it is only police officers as witnesses there would seem to be little harm if the accused has their disclosure. Crowns are sometimes concerned that an accused could put videos on the internet and so on. I think few would do it in such circumstances.
Of course there are cases where it is quite understandable that an accused has limited access to disclosure. In a sex assault, it would be quite traumatic if a complainant had their video statement posted online as a video.
Even if the accused is given disclosure, it cannot be used for an improper purpose. This is called “The Implied Undertaking Rule”. For instance, if there was an accused charged with a domestic assault, no one can use evidence taken from the Crown disclosure in Family Court without a court order allowing it. Another example would be evidence from a DUI case from criminal court being used in civil proceedings against the alleged drunk driver. A court order must be obtained first.
If you are in a jurisdiction that allows you to have disclosure yourself, you must not share it with or give it to anyone. If you are in a county where the rules are more restrictive, make an appointment to review the evidence against you at your lawyer’s office. You should also bring a list of questions you might want to ask your lawyer.