How police obtain and use your information, and what your rights are when you are a witness, suspect, or accused.
TL;DR
Police generally need judicial authorization (a warrant or production order) to obtain your personal information, thanks to Charter section 8. Narrow exceptions include exigent circumstances and some open-source information. Stronger protections apply to phones, health records, and private communications.
Production orders and warrants
Under the Criminal Code, police must obtain judicial authorization for most investigative steps involving your private information, including:
Production orders to compel a company to hand over records.
General warrants for novel investigative techniques.
Part VI authorizations for intercepting private communications.
Tracking warrants for device location data.
Charter protections at play
Section 8 (unreasonable search), section 7 (life, liberty, security of the person), and section 10(b) (right to counsel) all protect against improper privacy intrusions in criminal investigations.
Access to your own file
You can request access to a police file about yourself under the applicable provincial law (e.g., MFIPPA in Ontario). Access may be refused if disclosure would harm an ongoing investigation or reveal confidential informants.