A former Met Police officer who sued the force for wrongly using its powers to investigate her has won a case over a breach of human rights and misuse of private information.
Ex-Detective Constable Andrea Brown was probed after going on holiday with her daughter while on sick leave.
She says she was left "emotionally, mentally and financially drained" by her battle against her former employer.
The Met said it would not make a full comment until damages were finalised.
The civil case at Central London County Court heard police cited an act of Parliament which did not exist to obtain personal data on their own officer - prompting surprise from the judge.
For many years a photograph of Ms Brown on patrol at a football match hung proudly on the wall of the reception area in New Scotland Yard and she eventually became a detective constable.
But she resigned from the Met in November 2013 after a 20-year career, recalling: "I lost all my confidence and sense of self worth and, at times, I felt close to a complete nervous breakdown."
To fund the £80,000 costs of the case, Ms Brown had to sell her house in South Croydon, and borrow savings from family members.
Ms Brown, who is in her 40s, told the BBC: "I have gone from having a well paid job and living comfortably to always worrying about money."
She joined the police service in 1993 but while on sick leave for depression in 2011 her father died of cancer and she decided to take her mother and 14-year-old daughter to visit their wider family in Barbados for two weeks.
She told her Police Federation representative about the trip, but not her line manager.
Her failure to do so did amount to a minor disciplinary matter, but senior officers at Sutton police station in south London used powers designed to investigate crime to obtain personal data on their colleague.
Det Insp Sarah Rees approached the National Border Targeting Centre (NBTC), a division of the UK Border Force operated by Greater Manchester Police.
She also approved an application to Virgin Atlantic to obtain details of Ms Brown's air travel, which cited the non-existent Police Act 2007.
Ms Brown said: "She hadn't given a reason why she wanted the information... she hadn't got it authorised. But yet she was able to get details of my and my daughter's travel, and obtained five years' worth of information about my travel movements."
Ms Brown sued the Met Police and Greater Manchester Police for breach of data protection, human rights, and misuse of personal information.
Shortly before the hearing both forces admitting breaching the Data Protection Act and Ms Brown's right to respect for her family and private life under Article 8 of the Human Rights Act.
In July, the court ruled both forces had misused private information, although a claim for misfeasance in public office failed.
Judge Jan Luba QC was withering about Det Insp Rees, saying she appeared "glib, almost flippant", and he expressed his astonishment at her "loose and casual grasp of the law".
Ms Brown's solicitor advocate David Gray-Jones said: "What is significant is that the judge commented that the senior police officers involved in this case didn't appear to have any appreciation or understanding of the laws that regulate their conduct in this area, and didn't acknowledge that they had done anything wrong."
But Andrea Brown's experience may be far from a one off.
In July, the group Big Brother Watch which campaigns on data and privacy protection, published a report entitled "Safe in Police hands?" It found that between June 2011 and December 2015 there were at least 2,315 data breaches by UK police staff.
In a statement, the Met Police confirmed the court decision but highlighted the fact it had successfully defended Ms Brown's civil claim for misfeasance in a public office.
It added: "A final judgement and ruling on damages is awaited from the court and expected in the near future. Therefore, at this stage we will not be commenting further on the case."
A spokesman for Greater Manchester Police said: "We acknowledge the findings of the court."
Det Insp Rees has now retired from the Met and declined to comment. No officer has been disciplined as a result of the case.
For her part, Ms Brown believes an important point of principle about police behaviour was at stake.
"They are the ones who are supposed to be upholding the law, and protecting members of the public by chasing after people who have broken the law - criminals," she told the BBC.
"I am not a criminal, my daughter is not a criminal. I can't understand why they would feel justified in taking the action they did. It was totally excessive."