An arrest in Canada is unlawful when police lack lawful authority to arrest — most often because they did not have the reasonable grounds the Criminal Code requires — or when the arrest is arbitrary under section 9 of the Charter . Not every police mistake automatically voids an arrest, and not every Charter breach means charges disappear. The core questions are: Did police have legal power to arrest? Was the detention arbitrary? What remedy follows if they got it wrong?
The Criminal Code sets when police may arrest. The Charter and court decisions police those powers.
Under s. 495(1), a peace officer may arrest without warrant:
Section 495(2) then limits warrantless arrest for certain hybrid and summary offences where the public interest can be satisfied without arrest and the officer has no reasonable grounds to believe the person will fail to attend court. In plain terms: arrest is not always the default tool, even when an offence is alleged.
Warrant arrests are authorized through Code provisions governing issuance and execution of warrants (including the Part XXVIII forms framework). As with warrantless arrests, the underlying information must support reasonable grounds that the person may have committed the offence, and police must follow the processing, detention, and release rules that apply after arrest.
Section 494 allows a private citizen, in defined circumstances, to arrest a person found committing an indictable offence, or a person being freshly pursued after apparently committing a criminal offence. Citizen’s arrest is tightly constrained and easily goes wrong; it is not a general licence to detain people.
An arrest is typically vulnerable when:
In Storrey , the Supreme Court held that reasonable and probable grounds must be subjectively held by the officer and must also be justifiable from an objective point of view — a reasonable person placed in the officer’s position would be able to conclude that the grounds existed. Hunch, speculation, or a one-sided incomplete investigation can fail that test.
A concrete public example is the Brantford case involving then-OPP Inspector June Dobson: charges connected to alleged fraud involving Wayne Gretzky memorabilia were later withdrawn after the arrest warrant relied heavily on statements from a cognitively impaired witness that did not hold up. Dobson later pursued a multi-million-dollar civil claim alleging arrest without reasonable and probable grounds. Whatever the civil result, the episode illustrates how weak grounds can collapse both the prosecution and the lawfulness narrative around the arrest.
Procedural errors matter, but they are not always the same thing as an unlawful arrest. Courts distinguish between:
Section 9 gives everyone the right not to be arbitrarily detained or imprisoned. An arrest without the reasonable grounds the law requires is the classic arbitrary-arrest pathway. The remedy analysis then turns on the facts and the evidence the Crown wants to use.
Everyone arrested or detained has the right to:
These rights are critical. Failure to comply can support Charter applications. That said, a s. 10 breach does not automatically equal “the arrest had no legal basis,” and it does not automatically end the prosecution. Defence counsel separate the authority-to-arrest issue from the rights-on-arrest issue.
If you spend a long period in custody without being told why you are held, or without a meaningful opportunity to speak with counsel, tell your lawyer immediately. Timing of judicial interim release / bail hearing issues can also matter to the detention analysis.
Related search-and-seizure questions — for example, whether a search after arrest was lawful — are adjacent but distinct. A search incident to arrest collapses if the arrest itself was unlawful; see also warrantless car or home searches where the stop-and-search path is the issue.
Possible consequences of an unlawful or Charter-breaching arrest include:
None of these outcomes is guaranteed. The strength of the grounds, the seriousness of any breach, and the importance of the evidence all affect what a court or Crown will do.
A practical defence sequence usually looks like this: obtain disclosure and the grounds narrative; separate authority to arrest from post-arrest Charter compliance ; decide whether a s. 9 or s. 10 application is realistic; and only then weigh civil options. Civil litigation is a different forum with different proof and limitation issues — it is not a substitute for the criminal defence.
If you believe police unlawfully arrested you in the Greater Toronto Area, consult with the experienced Mass Tsang legal team . We are familiar with arrest-authority and Charter issues across GTA courts and can assess whether the grounds, the detention, and the post-arrest process give you a real defence issue. For criminal defence needs in the GTA, contact us for a free consultation.
