The law needs to be updated to regulate the growing number of household CCTV cameras, a human rights group has said.
A home CCTV camera helped to convict the killers of Garry Newlove
More people are installing their own devices to deter vandalism and anti-social behaviour.
Liberty says legislation is needed to take this into account, particularly where the cameras monitor public places such as parks and pavements.
In one case, images from a neighbour's CCTV helped to convict three teenagers who kicked to death a father-of-three.
Garry Newlove, 47, died after he confronted a gang outside his home in Warrington, Cheshire, in August 2007.
Retailer Maplin says its sales of cameras, monitors and recorders have gone up 265% in the past five years.
One man - who lives near Glasgow bought a camera after his car, parked behind his house, was vandalised by a gang of drunken teenagers.
The man, who wants to be known as "Joe", said: " They used to hang around in crowds at the shops - now they just veer clear because of the camera.
"It's a case of looking after your own property, if you don't do something about it nobody else will."
But Gareth Crossman from Liberty said: " Not many people know that if their camera looks onto public or a neighbour's property they are bound by the data protection act and they must comply with some very severe restrictions."
The police, too, say CCTV cameras need to be used properly - otherwise they may not be able to be used in evidence , and their images could be challenged in court.