Canadian criminal justice: Investigation & arrest

5 - Investigation & arrest

The purpose of an investigation is to identify, gather, and preserve evidence of suspected offences, which may be used against a person in criminal proceedings.

The investigation of an offence may be a matter of minutes or a matter of months. In simple impaired driving cases, the investigation may begin with a police officer’s observations during a “RIDE program” and end with a “Breathalyzer” test a few hours later. In complex drug cases, the investigation may begin with a confidential informant’s tip and end with wiretaps and search warrants being executed over a year later. Investigations may continue even after charges have been laid.

The authorities have many investigative tools, but individuals also benefit from broad and liberal rights under the Canadian Charter of Rights and Freedoms that restrict improper investigations.

  • The most basic evidence-gathering tools for police officers include police observations, witness interviews, review of security camera footage, and forensic examinations.
  • In certain circumstances, police officers have the power to search persons and places in certain circumstances and to seize potential evidence. However, section 8 of the Charter protects everyone’s right against “unreasonable search and seizure.”

Search and seizure powers include simple pat-down searches, invasive wiretaps and computer searches, seizure of bodily samples (e.g. breath, urine, or blood), and physical searches of homes and businesses. The authorities often keep seized property in their custody until the end of the court proceedings and may even keep the property permanently through special “forfeiture” powers.

  • Police officers have the power to detain or arrest individuals during investigations. However, section 9 of the Charter protects everyone’s right “not to be arbitrarily detained or imprisoned.” Furthermore, section 10 of the Charter protects a person’s right to “be informed promptly” of the reason for their detention or arrest and their right “to retain and instruct counsel without delay and to be informed of that right.”

Detention and arrest powers include temporary “investigative detentions,” random roadside vehicle stops, “bench warrants” for missed court appearances, and special “Feeney warrants” for arrests made inside a person’s home. Detention and arrest may or may not involve handcuffing and transportation to a police station.

  • Police officers also have the ability to interview suspects. However, section 7 of the Charter protects the right of every person to remain silent in the face of police investigation. Furthermore, under the Youth Criminal Justice Act, young persons have additional rights during police interviews, including the right to have a parent present during the interview.

Information obtained from a suspect during a police interview can be used against them in criminal proceedings in several ways. Sometimes, an interview may lead the suspect to make admissions of guilt. For example, a suspect might admit to police that they committed an assault against their spouse, even though their spouse changes their story about the allegation at trial. Sometimes, an interview may lead the suspect to say something factually incorrect, either intentionally or unintentionally. For example, a suspect might accidentally confuse two different events during their interview, which could be used in court to show that the suspect is an unreliable witness. However, if a suspect does choose to remain silent, then their silence cannot be used against them in court. In other words, judges and juries are not allowed to say that "since the defendant did not talk to police, they must be hiding something."

The line between police powers and civil liberties is fluid and ever-changing.

  • In some circumstances, a person may have the right to reasonably resist an unlawful police investigation. However, the Criminal Code also punishes people for obstructing justice, assaulting police, disarming police, obstructing police, or resisting arrest. If a person is unsure about their rights or obligations during a police investigation, they should immediately seek the advice of a lawyer.


  • In some circumstances, if the police investigation has infringed a person’s rights, the person can bring a pre-trial application to have the evidence excluded from the trial under section 24 of the Charter.

Every person in Canada has the right to consult a lawyer, but that right may be limited once a person is detained or arrested and a person may lose important advantages once they have been charged with an offence. It is never too early or too late to consult a lawyer about a potential, ongoing, or completed investigation. Our lawyers are available to offer advice for people at all stages of an investigation, both before and after arrest.

Contact the lawyer of your choice for a free consultation.

This blog post is part of our Canadian criminal justice series – we hope that these blog posts will shed some light on the Canadian criminal justice system for clients and potential clients, members of the community, and law students. Feel free to e-mail us at to propose any changes or updates.