Police powers and the rule of law: where authority comes from

Professor Desjardins opens the course by putting a pair of handcuffs on the desk. 'Every one of you will be able to buy a pair of these online for less than the price of a textbook,' he says. 'What you cannot buy is the authority to use them. That comes from the law, and only from the law.' He tells the class that this course is about the moments when a police officer interferes most directly with someone's freedom: stopping them, arresting them, searching them, their car, their phone or their home, and deciding whether they go home or to a cell. In LES-111 the class studied the rights that limit police. Here they study the powers themselves, one at a time, and the practical steps that make each use of a power lawful.

He writes a single sentence on the board: a police officer may do only what the law authorizes, while a private citizen may do anything the law does not forbid. The rule of law, he explains, turns that sentence into a daily discipline. Before an officer stops, arrests or searches, they should be able to answer three questions: what power am I using, where does it come from, and what facts give me the grounds the power requires? An officer who cannot answer all three is not exercising a police power. They are guessing, and a court will treat the result accordingly.

Why police powers are limited

The class discusses why a free society limits the powers of the people it pays to protect it. Jesse Morningstar points out that his community has a long memory of police powers used without limits, from the enforcement of laws that controlled where First Nations people could live and travel to the removal of children. Linh Tran adds that her cousin Bao, stopped four times in a year while walking home, never understood which power was being used or why. Desjardins agrees that both experiences explain why the law insists on clear powers, clear grounds and clear records. Limits on power are not obstacles to good policing. They are what makes police authority legitimate, and legitimacy is what makes people call the police, give statements and testify.

There is also a practical reason. Evidence obtained by an unlawful arrest or search may be excluded, a lawful charge may collapse, and the officer may face a complaint, discipline or a lawsuit. Section 24(2) of the Charter allows a court to exclude evidence obtained in a manner that infringed a Charter right if admitting it would bring the administration of justice into disrepute, and section 24(1) allows other remedies, including damages in some cases. Desjardins tells the class that he has watched strong cases fall apart, not because the accused was innocent, but because an officer could not explain which power they used.

Statutes: the Criminal Code and provincial laws

Most police powers in Canada are written in statutes. The Criminal Code contains the main arrest powers in sections 494 and 495, the powers to enter a dwelling to arrest in sections 529 to 529.5, the general search warrant in section 487, telewarrants in section 487.1, warrants for bodily substances and tracking devices, the release provisions in Part XVI, and the duties of officers who seize things in sections 489 and 489.1. Provincial statutes add powers that apply in their own fields: Ontario's Highway Traffic Act gives the power to stop vehicles in section 216, the Liquor Licence and Control Act and the Trespass to Property Act give powers to arrest or remove people in certain circumstances, and the Mental Health Act gives police power under section 17 to apprehend a person who appears to be at risk of serious harm. Federal statutes such as the Controlled Drugs and Substances Act add search powers in their own areas.

Desjardins tells the class to read the statute itself, not a summary, when a power matters. Statutes use precise words, and the precise words set the limits. A power to arrest a person found committing is narrower than a power to arrest a person the officer believes has committed an offence, and the difference has decided many cases. He shows how the service's legal advisor annotates the training binder with the exact wording of each power and the leading decisions that interpret it, and recommends that each student build a pocket version for the powers they will use most.

The common law and ancillary powers

Not every police power is in a statute. Canadian courts recognize that police have common law duties, including preserving the peace, preventing crime and protecting life and property, and that they may have ancillary powers reasonably necessary to carry out those duties. The test comes from an English case, R. v. Waterfield (1963), adopted by the Supreme Court in Dedman v. The Queen in 1985: first, does the police conduct fall within the general scope of a duty imposed by statute or recognized at common law; second, is the conduct a justifiable use of police powers, considering how necessary it is, the importance of the duty to the public good, and the extent of the interference with individual liberty? Courts have used this test to recognize investigative detention in R. v. Mann (2004), entry into a home in response to a disconnected 911 call in R. v. Godoy (1999), safety searches in R. v. MacDonald (2014), and the authority to establish sobriety checkpoints. They have also used it to refuse powers, as in Fleming v. Ontario (2019), where the Court held that there is no common law power to arrest a person acting lawfully in order to prevent a breach of the peace by others.

Desjardins warns the class that ancillary powers are the riskiest ground for an officer. A statutory power has clear words; a common law power exists only to the extent a court has said it does, and its limits are defined case by case. When an officer relies on a common law power, they must be able to explain the duty they were performing, why the step was reasonably necessary, and why no less intrusive option would do. Fleming is his favourite example: an officer who arrested a man carrying a flag near a protest, to protect him from a hostile crowd, believed he was preventing violence, but the Court held that the law gave him no such power over a person behaving lawfully.

Powers, duties and discretion

A power is permission, not an obligation. Most powers are framed as may, not shall: an officer may arrest, may search, may stop. Discretion fills the space between what the law allows and what the situation needs. LES-105 explored the ethics of discretion; here the class looks at its legal shape. Section 495(2) of the Criminal Code directs officers not to arrest without a warrant for summary conviction, hybrid and certain indictable offences where they believe on reasonable grounds that the public interest, including the need to establish identity, preserve evidence and prevent the continuation or repetition of the offence, can be met without arrest, and where they have no reason to believe the person will fail to attend court. The principle of restraint in section 493.1, added in 2019, tells officers and justices to give primary consideration to release at the earliest reasonable opportunity and on the least onerous conditions.

Some situations remove discretion. Policies on intimate partner violence often require or strongly prefer an arrest when there are grounds, and officers must follow a valid court order such as an arrest warrant. Desjardins notes that a policy cannot create a power the law does not give: a department can tell officers to arrest whenever there are grounds, but it cannot authorize an arrest without grounds. A policy can, however, restrict a power: a department can forbid certain searches, require supervisor approval for others, or require body-worn camera recording.

Grounds, records and accountability

Every power in this course depends on grounds, the facts that justify using it. The class will study the different standards in Lesson 2. For now Desjardins stresses one habit: write down the facts, not the conclusion. 'He looked suspicious' is a conclusion; 'he matched the broadcast description, was three blocks from the scene four minutes after the alarm, and was carrying a backpack with drill handles sticking out' is a list of facts a court can assess. Officers who record facts at the time can explain their decisions months later. Officers who record conclusions are left trying to remember.

He also describes the records that the service keeps on the use of powers. Port Ardent tracks arrests, investigative detentions, searches of persons and vehicles, strip searches, warrants applied for and executed, and releases, along with the time each step happened. Sergeant Lisa Haddad uses the data to find officers who need coaching and practices that need review. The program below shows the kind of summary she prepares each month from the service's records of arrests and the power used for each.

# Port Ardent arrests in one month, by the authority relied on
arrests = {
    "warrantless, grounds to believe": 168,
    "found committing": 74,
    "arrest warrant": 41,
    "breach of release conditions": 29,
    "mental health apprehension": 22,
}
total = sum(arrests.values())
print("total arrests:", total)
for power, n in sorted(arrests.items(), key=lambda kv: -kv[1]):
    print(f"{power:34} {n:4}  {n / total:.2f}")
with_warrant = arrests["arrest warrant"]
print("share made on a warrant:", round(with_warrant / total, 3))

total arrests: 334
warrantless, grounds to believe     168  0.50
found committing                     74  0.22
arrest warrant                       41  0.12
breach of release conditions         29  0.09
mental health apprehension           22  0.07
share made on a warrant: 0.123

Only about one arrest in eight was made on a warrant. Most were made on the officer's own assessment of the grounds, which is why the training in Lessons 2 and 3 matters so much: in the large majority of arrests, the officer is the first and often the only person who decides whether the grounds exist before a person loses their liberty. Mental health apprehensions are a different power entirely, under the Mental Health Act, and Desjardins notes that they are not arrests for an offence at all, though they involve the same physical restraint and the same need to record grounds.

A course roadmap

Desjardins walks the class through the course. Lessons 2 to 5 cover powers over the person: the standards of grounds, arrest without a warrant, arrest warrants and the practical steps of an arrest, and investigative detention. Lessons 6 to 10 cover searches: search warrants, searches incident to arrest, consent and the other exceptions, vehicles and digital devices, and entry into homes. Lesson 11 covers release, judicial interim release and the care of people in custody. Lesson 12 brings everything together in a powers review of the Lakeshore Hardware file the class has followed since LES-104.

He reminds the class that the night of March 14, 2026, involved almost every power in the course. Officer Patel detained Kyle Brandt on Pine Street at 02:29:15. Constable Dev Malhotra's unit arrested him at 02:29:40. The officers searched his backpack and found three cordless drills and a reciprocating saw with serial numbers matching the store's records. They seized his phone. Investigators later obtained a warrant to search a garage he rented. A decision was made about his release. Each step used a different power with different requirements, and each will be examined in the lessons ahead.