Harvey Levin studied law and cut his media teeth during the O.J. Simpson trial. Photo / AP

Harvey Levin studied law and cut his media teeth during the O.J. Simpson trial. Photo / AP

Harvey Levin's day in Los Angeles usually begins at about 3am. He is going to work just as the celebrities on whom his website and TV show, TMZ, reports are leaving the nightclubs, falling into bed with each other or drinking one final round of shots.

The world of celebrity never seems to sleep and neither, it appears, does Levin. The 58-year-old rises early and heads to the office, usually breaking off for a gym session. He regularly puts in 12-hour days, ringing sources, viewing videos and hosting news meetings.

Such a regime perhaps explains why he has become one of the most influential names in Hollywood and, increasingly, the world beyond it.

TMZ has become a huge force, breaking stories that create headlines around the globe and pioneering new forms of journalism. It has pushed the boundaries of what journalism means, not only breaking old-fashioned scoops, but also relying on video content sent in by a vast network of staff, contacts and ordinary people.

To his critics, Levin and TMZ represent the public face of modern media obsessed with celebrities and their meaningless antics. The methods TMZ employs illustrate an era where nothing is private any more and anything can be caught on video by someone with a cellphone.

To his defenders, he is a wildly successful journalist - responsible for scores of scoops - who is following in a long tradition of gossip journalism that harks back to the 1920s and 1930s.

The one thing everyone agrees on is Levin's power. TMZ has earned him the sobriquet the King of Hollywood; a title bestowed on many but earned by few. But Levin certainly seems to fit the bill and now TMZ's growing influence has run up against an unexpected opponent: the Los Angeles County Sheriff's Department.

Two weeks ago news broke that the police had obtained Levin's phone records with a secret warrant as part of an investigation into who leaked details of the drink-driving arrest of actor Mel Gibson to TMZ in 2006.

The astonishing story has turned Levin into an unlikely champion of press freedom. "It is a fight about the first amendment, a fight about democracy. It is a fight about the freedom of the press," he told a Los Angeles news conference.

Levin, who is backed by press freedom groups, has a point. But the story has also revealed that - in a state where the governor is a former movie star - reporting on celebrity can upset the powerful. It also serves as a warning for TMZ's ambitions.

TMZ reporters are already crawling the corridors of power outside LA, heading to Congress to catch politicians unawares. As TMZ grows and spreads its tentacles to Washington and beyond, Levin's biggest battles may just be about to begin.