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Reasonable grounds for arrest and unconstitutionally obtained information

February 22, 2024  By Mike Novakowski

Photo credit: Pict Rider / Getty

Canada’s highest court has ruled that information obtained from non-Charter compliant police conduct must be excised from an officer’s grounds when reviewing the basis for an officer’s warrantless arrest.

In R. v. Zacharias, 2023 SCC 30, the accused was stopped by police for equipment violations. The truck he was driving had tinted windows and a burnt-out light. Over the course of the police interaction with Zacharias and after querying his name in police databases, an officer developed a suspicion that Zacharias may be in possession of controlled substances. The officer had significant training and education in the interception and detection of travelling criminals on the highway, including conducting some 12,000 to 15,000 traffic stops and teaching courses on traffic enforcement investigations. The officer detained Zacharias and called for a sniffer dog. When the sniffer dog was deployed on Zacharias’ truck, it indicated the presence of drugs. Zacharias was arrested for possessing a controlled substance and his truck was searched. Duffel bags in the truck box were found to contain 101.5 lbs. of cannabis and $12,600 in cash along with other evidence. Zacharias was then arrested for trafficking and transported to the police station to speak with a lawyer.

At trial in the Alberta Court of King’s Bench, Zacharias challenged the officer’s reasonable suspicion to detain him for a drug investigation and for calling the drug sniffer dog. The trial judge agreed that the officer’s suspicion was unreasonable and that Zacharias’ Charter rights under s. 8 – unreasonable search or seizure – and s. 9 – arbitrary detention – were breached. She concluded that the officer’s information did not rise to the reasonable suspicion standard—missing it by a “minuscule” degree—and therefore Zacharias’ detention and the sniffer dog search were not justified. However, the trial judge admitted the evidence under s. 24(2) anyways and Zacharias was convicted of possessing marijuana for the purpose of trafficking. He was sentenced to 14 months in jail. A majority of the Alberta Court of Appeal confirmed the trial judge’s ruling in admitting the evidence and his convictions were upheld. A third judge would have excluded the evidence and entered an acquittal.

Zacharias again appealed, this time to the Supreme Court of Canada. Although the s. 24(2) analysis dominated the Supreme Court’s ruling, the five judges hearing the appeal also examined whether unconstitutionally obtained information must be automatically excised from an officer’s consideration when exercising a warrantless arrest power, as it is in the case of a search warrant and reviewing an ITO. Applying such a rule in the warrantless arrest context would require a reviewing judge to remove any unconstitutionally obtained information from consideration as part of the officer’s reasonable grounds. In this case, the grounds on which the officer relied to make the drug arrest was based on the unlawful sniffer dog search, which in turn led to the search of the truck and the resultant arrest for possession for the purpose of trafficking. If the sniffer dog hit was excised from the officer’s grounds, then the arrests and searches that followed would be rendered unlawful.


“Canadians have a legitimate expectation that the police will know and comply with the law, especially the Charter.” – Justices Rowe and O’Bonsawin

Four of the five Supreme Court judges hearing the case found automatic excision was required. Justices Rowe and O’Bonsawin ruled a court must excise grounds for an arrest that are based on evidence that is subsequently found to have been unlawfully obtained even though warrantless arrests are often carried out in dynamic situations:

The need to ensure that the state cannot rely on conduct that violates the Charter applies regardless of whether the police are knowingly in breach of the law. […] In order to ensure that the state is not able to rely on violations of the Charter, the reviewing judge must excise evidence that has been unconstitutionally obtained at the outset of this inquiry. […] In this inquiry, the court considers the totality of the circumstances known to the officer at the time of the arrest, but does not include evidence found to have been unconstitutionally obtained. […] Canadians have a legitimate expectation that the police will know and comply with the law, especially the Charter.”

However, an arresting officer may still meet the reasonable grounds standard for arrest even with information excised if the balance of the evidence suffices to establish reasonable grounds.

Justices Martin and Kasirer agreed with the automatic excision rule. “We accept the sound proposition that a lawful arrest cannot be based on unlawful grounds. More specifically, reasonable and probable grounds for arrest cannot be based on unconstitutional police misconduct.”

Justice Côté, however, did not agree that the police could not rely on unlawfully obtained evidence to satisfy the reasonable grounds requirement for arrest. In her view, the assessment of an officer’s grounds for arrest should not hinge entirely on a retroactive judicial assessment of the underlying sniff search rather than the circumstances known to the officer at the time of the arrest. “Judicial reflection is not a luxury an officer can afford. It is artificial and inconsistent with the reasonable and probable grounds standard to hold that an arrest made based on clear and reliable evidence of a crime is unlawful.”

As for the s. 24(2) analysis, three judges – Rowe, O’Bonsawin and Côté – would have nevertheless admitted the evidence, dismissed Zacharias’ appeal and upheld his convictions. Justices Martin and Kasirer would have excluded the evidence, allowed the appeal and entered an acquittal.

Mike Novakowski is Blue Line’s case law columnist.

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