An apology has been issued by Poole council after its spying on a family over a school place was ruled unlawful in a landmark case.

In a controversial use of a “snoopers charter”, which caused outrage nationwide, Jenny Paton and her family were subjected to three weeks of covert surveillance in 2008 by Borough of Poole.

Welcoming the ruling, her partner Tim Joyce, 40, said: “We are delighted the tribunal found in our favour and hope that it’s a small step to rolling back the Big Brother state we now live in.”

The local authority used the Regulation of Investigatory Powers Act, set up to fight terrorism and serious crime, to check if the family was living within the catchment area of popular Lilliput First School.

“The children were only three, six and 10, but they were referred to as ‘targets for surveillance’ – it wasn’t right,” said Jenny, 41.

“It’s been a long battle but we hope this result will help bring about a change in the way the law is used,” she said.

The Investigatory Powers Tribunal, set up to investigate complaints, ruled in the family’s favour in the first challenge to take place at an open hearing.

In a 27-page report it ruled the use was not a proper purpose and nor was it necessary to use the surveillance powers.

John McBride, chief executive of Borough of Poole said: “The council accepts fully the ruling of the Investigatory Powers Tribunal and would like to apologise to Ms Paton and her family for any distress caused as a result if its actions in this case.”

Tim said they appreciated the apology and were not seeking any kind of financial compensation.

“It’s about protecting the population from overzealous minor officials and making sure the laws are only used in a way that is purposeful, reasonable, necessary and proportionate,” he said.

Backed by Liberty, the family took their case to the tribunal in November 2009, which also found the surveillance breached the family’s right to privacy under Article 8 of the Human Rights Act.

The council argued it was “minimally invasive of privacy” and it no longer uses the powers for school admissions. However it has been used on fishermen, for under-age alcohol sales and vandalism.

Mr McBride said: “Overall, the council’s use of Ripa powers has been extremely limited. Nevertheless, it is vital that the public has confidence in the use of surveillance methods by all public agencies, including local authorities.”

Corinna Ferguson, legal officer for Liberty said: “Intrusive surveillance is vital to fighting terrorism and serious crime but weak legal protections and petty abuses of power bring it into disrepute. Former ministers claimed that the innocent had nothing to fear but the sinister treatment of Jenny and her kids proves that these powers need to be far more tightly restricted and supervised.”