It is claimed a council official documented Ms Paton's movements
A woman was spied on by her council 21 times to find out whether she lived in the catchment area of a school, a tribunal has heard.
Jenny Paton, 40, is taking Poole Borough Council to a tribunal over its use of the Investigatory Powers Act.
The mother-of-three claims a council official documented her movements and those of her partner, Tim Joyce.
The Investigatory Powers Tribunal heard the surveillance occurred over three weeks around last February.
It is claimed the council used its investigatory powers to find out whether the family lived at an address in the catchment area for Lilliput First School.
Gordon Nardell, representing the family, told the tribunal the case was about "liberty" and the "extraordinary powers" of local authorities.
He said: "The complainants have and were found to have played by the rules but this local authority played fast and loose."
Mr Nardell also told the hearing Ms Paton's family could have been proven to have been living in the right area by other means than spying.
He said it was "quite extraordinary" that the surveillance - over three weeks last February - was authorised.
Investigators were watching "comings and goings" from the family's home address and following a car, he said.
Mr Nardell added: "There is plainly an interference with home life."
The Regulation of Investigatory Powers Act (Ripa), which sets the parameters of public bodies' use of surveillance, was introduced in 2000.
The hearing is expected to last two days.