The highest body of the European Court of Human Rights (ECHR) ruled in favour of a 38-year-old Romanian man who claimed his rights had been violated when he was sacked in 2007 for sending private chat messages in the office.
Bogdan Mihai Barbulescu has fought a ten-year legal battle through Romanian and European courts, claiming his privacy had been infringed when his employer accessed intimate exchanges with his fiancee and brother.
In a first ruling in January last year, the ECHR found that the snooping was allowed because employers were justified in wanting to verify "that employees were completing their professional tasks during working hours."
But in a review, the 17 most senior judges at the Strasbourg-based court in France found Tuesday that Romanian courts "had not adequately protected Mr Barbulescu's right to respect for his private life and correspondence."
In a written judgement, backed by 11 votes to six, they found that previous court rulings had "failed to strike a fair balance between the interests at stake", namely the company's right to check on employees and employees' right to privacy.
The judges also found that "an employer's instructions could not reduce private social life in the workplace to zero", meaning that some use of the internet at work for personal reasons was justified.
The ruling will become law in the 47 countries that have ratified the European Convention on Human Rights, meaning some members will have to adjust their national legislation.
Sex life exposed
The case revolved around messages sent in 2007 by Barbulescu over the Yahoo messenging platform, which the software engineer was required to use by his bosses to liaise with clients.
Barbulescu argued that his employer had invaded his right to privacy by using spyware to access the chat material which included details about his health and sex life.
In their judgement on the court's website, the ECHR judges said Tuesday that it was unclear whether Barbulescu had been warned about the monitoring or the risk of the messages being read without his authorisation.
It also said that Romanian courts had failed to determine why the monitoring measures were justified and whether there were other ways of checking on him "entailing less intrusion" into his private life.
The judges held a hearing on November 30 last year, at which it heard arguments from experts and the European Trade Union Confederation.
The union group criticised the initial ruling last year, judging it to be too harsh.
It recommended that a verbal warning should be the first stage of any disciplinary process with dismissal only possible for repeat offenders or serious misconduct.
Experts also say that companies should also have a clear policy governing the use of professional software and the internet during work hours.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)