Journalists are an essential and powerful part of democracy. Do they use their power for good or ill? How free should they be? Should politicians be holding the press to account or should journalists be holding politicians to account? Hopefully the Leveson Inquiry will help to answer those questions.
To my mind it is valid that journalists sometimes bend the laws if the outcome is good for democracy. For example, the MP's expenses information were acquired illegally. Yet allowing press barons to use their powers to blackmail politicians is wrong. As is breaking the law in pursuit of tittle tattle, bribing the police or stalking celebrities.
Perhaps a legal definition of what is in the public interest would help clarify legal proceedings. If there were such a thing, in the future, when journalists are prosecuted for breaking the law they may pull out this as a "get out of jail for free" card and demonstrate that their actions were in the public interest. It would reinforce their freedoms yet define the limits of their remit.
So how would we define "in the public interest"?
Rooting out hypocrisy and lying by politicians should be part of it. Identifying those that abuse public office fits too. And, of course, crime. However, it does not include outing the private lives of celebrities.
To prevent the press from fishing for "dirt" using dubious means, there should also be a legal requirement that they have some evidence, however circumstantial, before they initiate an investigation. Without this a court may rule that their "get out of jail" card is invalid.