Canadian police can conduct a limited search of criminal suspects' mobile phones when they are arrested without getting a search warrant, but they must follow strict rules, a divided Supreme Court of Canada ruled Thursday.

In a 4-3 decision, Canada's top court said the search must be directly related to the circumstances of a person's arrest and police must keep detailed records of the search. It is the first time the Supreme Court has ruled on mobile phone privacy, an issue that has spawned a series of divergent lower court rulings.

The high court dismissed the appeal of a 2009 armed robbery conviction of Kevin Fearon, who argued unsuccessfully that police violated his rights when they searched his phone without a warrant after he'd robbed a Toronto jewelry kiosk.

The court agreed that the police had breached Fearon's rights, but the evidence against him on his phone should not be excluded.

"The police simply did something that they believed on reasonable grounds to be lawful and were proven wrong, after the fact, by developments in the jurisprudence," Justice Thomas Cromwell wrote for the majority.

Cromwell said the court was trying to strike a balance between the demands of effective law enforcement and the public's right to be free of unreasonable searches and seizures under Canada's Charter of Rights and Freedoms.

Three dissenting justices said police should need a search warrant in almost all cases.