For years, the city has been using Google Earth and Maps to peer into the backyards of residents as it investigates possible bylaw infractions.

City officials use tools such as Google Earth, Google Street View and Geographic Information Systems mapping to look down on homeowners and compare images from year to year to see when a landowner built a shed where it shouldn't be, or an illegal addition on their home.

We're not looking. It's Google Maps that's looking. - John Lane, city manager of building inspections

The city says it will use the Google tools to help enforce a new pool fencing bylaw that will require fencing around all four sides of a backyard pool.

Before this technology, inspectors and bylaw officers relied on neighbour accounts and supplied photos to see which infractions were new. Now they use Google to decide which cases to pursue – and in some cases, help prosecute them in court.

Any prosecutions are accompanied by site visits and other investigation, said John Lane, manager of building inspections.

"It's a piece of evidence," Lane said. "It's not the evidence."

There's a statute of limitations to fining homeowners for illegal work.

The city has a year from the time an official first investigates a case to lay a building code charge. Homeowners often say something has "always been there," Lane said. Google tools and GIS, with their year-to-year comparisons, help prove that's not the case.

The information is publicly available, Lane said. And he's never gotten any complaints.

"We're not looking," Lane said. "It's Google Maps that's looking. We're just using the information we receive from Google Maps. We don't ask Google Maps to take photographs of people's backyards."

Drones are now for sale in Wal-Mart so your neighbours can spy on you and collect your data. - Paula Gardner, McMaster University expert

Last year, the city laid about 400 Ontario Building Code charges against people who built without permission. About 100 of them resulted in fines.

Sheds, decks, barns, dormers, front porches, swimming pool enclosures and finishing basements all need a building permit, Lane said. Fines are usually between $1,000 and $2,000.

Call before you build

"It's very important they get a permit before they build," he said.

James Buffett, a municipal law enforcement supervisor, said overhead tools help with enforcing numerous bylaws, including property standards, zoning and vacant building registry and yard maintenance.

He uses Google tools and GIS mapping together. Sometimes he uses Google tools to get an initial idea of what the property looks like. Other times, it's to see how far back a violation goes.

Paula Gardner, a McMaster University associate professor of communications and multimedia, doesn't love the idea.

Law enforcement increasingly uses such tools for investigations, she said. People say they don't worry because they have nothing to hide. But Gardner said that's a "slippery slope argument" often made by people in demographics that can't foresee themselves being targeted.

Do you trust your neighbour with a drone?

"One day, you might be the profiled person whose data is considered interesting data that puts you into an at-risk category," she said.

The more data is used about you, "the more likely you're going to fit into a scenario," she said. "That's how people end up on no-fly lists, or how people end up as subjects in potential police investigations because they were in a certain place at a certain time."

The city usage is an example, she said, of how widespread surveillance is and how widely it's used. And people should be mindful of it.

"Drones are now for sale in Wal-Mart so your neighbours can spy on you and collect your data," she said.

"We have the obligation as citizens to weigh in on what our community standards are around these things."

samantha.craggs@cbc.ca | @SamCraggsCBC