An Ontario's man recent discovery that someone covertly attached a GPS tracking device to his vehicle led to a police probe but few answers as to who did it.

The GPS device discovered under Ben Ferrill's truck was sold by a U.S. company. (CBC)

The device was sold by an American company, U.S. Fleet Tracking, which sells GPS systems to companies that want to track their fleet vehicles. U.S. Fleet's website makes it clear the company does not give up information easily, even to American authorities.

The events led for calls from the Ontario man and his lawyer for Canadians to realize how the technology can be used.

Q: What is a GPS tracker?

A: GPS trackers rely on the Global Position System satellite navigation network to calculate location. Some devices simply log the information, while others send the data to servers.

Q: Can police put a GPS tracker on your vehicle?

A: Police or public officers need a warrant to attach an electronic tracking device in or on any thing, according to the Criminal Code of Canada. The warrant is valid for up to 60 days, but can be extended by a judge.

Q: Can anyone else use GPS trackers legally?

A: GPS devices can be attached to a vehicle when the owner gives consent, such as vehicles owned by a rental car company.

Information that can be gleaned from a GPS tracker include the vehicle's location, its speed and direction, and where it stopped and started, says private investigator Bill Joynt, the president of The Investigators Group of Toronto.

"Reputable [private investigation] firms will not deploy a GPS unit unless it legal to do so," Joynt told CBC News.

Q: Can GPS be used to track cheating spouses?

A: Yes. But installation of a tracking device without the proper authorization — whether a warrant or the permission of the owner of a vehicle — could result in a mischief charge, some in the private investigation field caution.

Q: How else is GPS being used on vehicles?

Cheating spouses and teenagers using the family car are not the only situations where GPS tracking is being used. The CanDrive program, meant to improve the safety of older drivers, is using GPS technology to track the driving habits of almost 1,000 Canadian motorists over the age of 70.

The five-year program is studying factors such as the motorists' ability to obey traffic signs and the effect of climate conditions on driving. Part of the outcome of the program will be the development of a screening test to identify those seniors who can no longer safely drive.

Q: What other ways is GPS being used to track people's movements?

In the U.S., a company called GTX Corp. has patented the GPS Shoe, a walking shoe with a two-way GPS device embedded in it. The shoe is marketed as a way to track patients with Alzheimer's disease. The technology can be set so that a text message is sent to a user if the person wearing the shoes wanders out of a predetermined area.

There are also GPS-based devices for child tracking. Russell Thornton of Salt Lake City developed Amber Alert GPS in 2007 after he lost his three-year-old son in an amusement park for 45 minutes. The subscription service has been available in Canada since 2009. The company's AAGPS 2G device works wherever both a GPS and cellphone signal can be received.