The police use of infrared devices as surveillance tools on homes is not a violation of a person's right to privacy, Canada's top court ruled on Friday.

In a unanimous decision, the Supreme Court of Canada ruled that police can use the devices, which give a clear image of thermal energy or heat radiation, without obtaining a warrant.

The court ruled that the device can be used because it doesn't reveal any intimate details of a person's lifestyle "or part of his core biographical data."

In April 1999, the RCMP used a plane equipped with an infrared camera to fly over the home of Walter Tessling.

Two informants had told investigators that the home was being used as a marijuana grow operation. Without a warrant, police used the camera to see if heat was coming from the house.

Police later obtained a search warrant and found a large quantity of marijuana and several guns.

Tessling was charged with a variety of drug and weapons offences. At trial, he argued that the use of the infrared equipment was a violation of his Charter right to be free from unreasonable search and seizure.

But the court ruled that the device only showed that some of the activities in the house generate heat.

"The heat distribution information offered no insight into his private life and its disclosure scarcely affected his 'dignity, integrity and autonomy,'" the court said.