Gambling companies in Britain could be forced to overhaul their advertising practices after a betting firm was ruled to have unlawfully targeted a problem gambler who was bombarded with more than 1,300 marketing emails.

In a ruling at the high court, a judge found that Sky Betting & Gaming sent the man personalised marketing without proper consent after gathering hundreds of thousands of pieces of data about him and his gambling habits.

Documents submitted in evidence and seen by the Observer reveal how the company’s customer protection measures – supposed to cut off marketing to people considered high-risk – did not kick in even though he was spending all his wages. Instead, he was labelled a “high-value” customer who, when he stopped using the platform, the company was keen to “win back”.

A judge found that while he may not have opted out of marketing, the man was in the depths of a gambling problem and had not properly understood how his data would be used. Mrs Justice Collins Rice said his ability to give consent was impaired as he “was not making decisions … on a fully autonomous basis at all” and ruled that Sky Betting & Gaming’s use of his data was unlawful.

Campaigners said this weekend the ruling could have ramifications for the wider industry and called for an investigation into the potentially unlawful profiling and targeting of problem gamblers. The Gambling Commission has implemented a series of measures to ensure better safeguards for customers, but campaigners say the industry has repeatedly failed to identify gamblers who are at most risk of harm.

In England there are almost 1.6 million adults who gamble who may benefit from some type of treatment or support for harmful gambling, according to the Office for Health Improvement and Disparities (OHID).

The OHID reported in 2023 that the annual number of excess suicide deaths in England associated with problem gambling or a gambling disorder was between 117 and 496.

Will Prochaska, leader of the Coalition to End Gambling Ads, said the ruling revealed the “frightening” level of tracking and targeting used by gambling firms and said that Sky Betting & Gaming’s practices were “indicative of how the sector operates”. “We’re very concerned because we know this is widespread,” he said.

Charles Ritchie from the charity Gambling with Lives that supports families bereaved by gambling urged regulators to act. “Operators are using data and algorithms to target people with more incentives to gamble when they should be using that data to meaningfully intervene,” he said.

The case against Bonne Terre Ltd, trading as Sky Betting & Gaming, came after a man who lost £46,000 requested records of the data the company held on him. Through those documents and subsequent legal disclosures he discovered the company and its partners had collected hundreds of thousands of pieces of data that were used to profile and target him.

The data filled more than 2,400 spreadsheets and had been used to predict his behaviour and select him for targeted marketing campaigns. In 2017 and 2018 he was sent at least 1,389 marketing emails offering him free bets and special prizes and encouraging him to spend. He often deposited money as a direct result. He is now seeking compensation for financial losses and for the unlawful use of personal data. A further hearing is expected to decide how much he is entitled to. “I lost 10 years of my life to gambling. I believe I – and a lot of others – should have been protected better,” he said.

Flutter, which bought Sky Betting & Gaming in 2020, said that while it had made “significant changes” since the claimant’s experience in 2017-19, it fundamentally disagreed with the judgment and was considering an appeal. The Betting and Gaming Council, which represents gambling firms, declined to comment.

The case follows occasional interventions by the gambling and data regulators. The Information Commissioner’s Office reprimanded Sky Betting & Gaming last year for unlawfully processing people’s data through advertising cookies without their consent. In 2023, Paddy Power was fined £490,000 by the Gambling Commission for breaching social responsibility rules after sending a promotional push notification to customers who had signed up to exclude themselves from gambling.

But the claimant said he hoped the case would lead to a wider investigation into the gambling sector, which is heavily reliant on online tracking, profiling and marketing to push its products to customers.

Currently, many companies rely on consent as the basis for using similar practices to those detailed in the high court case. But the ruling raises the question of whether other companies that market to problem gamblers, who could be considered unable to freely consent due to the compulsive nature of their gambling, are also breaking the law.

The Gambling Commission said it expected all operators to be “carefully considering” the latest judgment along with the ICO ruling against Sky Betting & Gaming in September. “Operators can only collect and use data to attract customers in ways that comply with data protection laws, with a focus on preventing gambling harm,” a spokesperson said.

The Information Commissioner’s Office said: “Uncontrolled tracking intrudes on the most private parts of our lives and can lead to harm. We continue to monitor this area and will not hesitate to intervene when necessary.”