Google is being sued for $3 billion in the UK over allegations that YouTube tracks children, violating the UK’s privacy laws.

Google has been facing ongoing scrutiny over privacy and antitrust concerns, but this latest lawsuit could be one of its most expensive. The lawsuit was brought by Duncan McCann, a father of three. The lawsuit is supported by Foxglove, a tech advocacy group in the UK.

The lawsuit alleges that YouTube and Google are ignoring UK privacy laws designed to protect children. Instead, according to the lawsuit, YouTube is harvesting data from children watching videos and using that data to target the children with ads specifically designed to influence young minds.

“We think its unlawful because YouTube processes the data of every child who uses the service – including kids under 13,” writes Foxglove. “They profit from this data, as they are paid by advertisers to place targeted advertising on their YouTube website. They do all this without getting explicit consent from the children’s parents. Under the GDPR and UK law, corporations can’t process the data of kids under 13 *at all* without explicit parental consent. Parents haven’t agreed to the many ways YouTube takes kids’ data.”

The lawsuit comes as Google is facing other lawsuits claiming it continues to track users even after they opt out. Should McCann win his case, the repercussions for Google and YouTube would be profound.