"If you are flying it over someone else's property that's a civil aviation breach, and also potentially a privacy breach," he said.
"If you've got a drone that's always buzzing around a property that could be a crime ... that can come under harassment."
Halligan called the incident "creepy" and said it was worrying not knowing what the purpose of the gadget was.
"When I come around to my mum's house we spend a lot time outside, and now we don't know if a drone will be there."
Shera said if the drone had been recording, it would constitute a crime.
"That's taking recordings of people who are naked, or nearly naked."
He noted that the quality of drone cameras had improved a lot in recent years.
The drone had appeared at 7.30pm that evening, Halligan said.
It returned again a few days ago and was watching Rays in her bikini.
"She only realised when the neighbour came over from across the street and told her there was a drone above her."
One neighbour called the police and was told to call the Civil Aviation Authority (CAA), Halligan said.
"It is a private area - there should be repercussions. They can't just go and film in people's backyards. I don't want myself filmed getting changed in the backyard. It is not right."
The CAA said Civil Aviation Rules required people who wanted to fly drones over people's homes to get permission from the owners or residents beforehand.
If people suspected drones are being flown over their homes with criminal intent, they should contact the police immediately.
The Auckland Council said drones may be used in public places and parks managed by the council, but users must follow CAA rules.
A police spokesman said the CAA was the enforcement agency, but police were often called to deal with drones.
"If the [drone] operation causes a safety risk to persons, property or other aircraft – potentially breaching the rules - police will respond and take all the details for forwarding to the CAA.
