The actor, who’s starred in several recent Fox releases including Marmaduke and Percy Jackson, is one of several celebrities whose mobile phone was allegedly hacked by Glenn Mulcaire, a private investigator hired by Murdoch tabloid News of the World. Coogan has instructed London lawyers Schillings to complain to the Murdoch publishing empire, and Schillings has written to News International threatening to sue. Coogan could argue that his privacy has been invaded and data protection laws breached. It will now be up to the newspaper giant as to whether it chooses to settle or defies Coogan in court. News Corp has already paid out more than $1.6 million settling similar legal cases, while not admitting liability. If, as ex-News of the World editor Andy Coulson maintains, he didn’t know anything about phone hacking, News Corp will argue immunity. Only a tiny percentage of these cases ever end up in proceedings. Scotland Yard has told Schillings that Coogan was among thousands of people whose mobile phone details were found in Mulcaire’s possession.

Schillings, which recently represented Brad Pitt and Angelina Jolie against the News of the World, enjoys a fearsome reputation as an attack-dog litigator. “What Coogan is doing is the precursor before litigation,” Caroline Kean, head of litigation at media lawyers Wiggin tells me. London lawyers will doubtless be rubbing their hands at this latest twist in the News Corp phone hacking scandal, anticipating plenty more litigation. Other celebrities whose phones have allegedly been hacked include model Elle MacPherson, Paul McCartney’s ex-wife Heather Mills and royal princes William and Harry. “There could be a lot of litigation on the back of this,” says Kean. “The issue is whether News Corp did know about what was going on. Then it will be liable.”

What’s at stake is that Coulson is now head of communications for Prime Minister David Cameron, arguably the second most powerful job in the UK. It puts a former senior News Corp executive right at the heart of government. The government’s critics argue that the coalition just does whatever Murdoch wants when it comes to media policy. One MP has called for Rupert Murdoch to testify before a House of Commons committee investigating the scandal. News International was unavailable for comment.

Aslan Charles Kousetta, the London media law firm, tells me that Coogan could additionally complain to the Press Complaints Commission about the News of the World intruding into his private life. But the PCC is seen as a pretty toothless beast compared to a top-flight lawyer like Schillings.