Journalism is a bit like walking around a house at night. One window is brightly lit and the curtains are open. This is the one the residents of the house and their PR operatives would like you to look through. But a good journalist will snoop around the back and try and look through the darkened windows and in between partly drawn curtains as well.

I am indebted for the metaphor to Mike Smith, former editor of The Age and now one of the country’s leading spin doctors. He used this analogy in describing the role of public relations to a class of journalism students at RMIT a couple of years ago. His point was that lazy journalism can be captive to public relations, but that good journalism never is. Implicit was the idea that good journalists, those who do more than publish press releases, must necessarily snoop.

I have been remembering Mike Smith’s metaphor over the last few weeks as I followed the controversy over the British News of the World bugging the telephones of the Royal family. Now it seems snooping of this kind has been common among some journalists for many years. And some are arguing that it’s defensible.

So what are the parameters of acceptable journalistic snooping? Or to extend Mike Smith’s metaphor, when does trying to peer through darkened windows turn into opening the window and climbing over the sill?

It is clear that most members of the public are quick to condemn snooping by the fourth estate. Research by former journalist Denis Muller has shown that 76% of ordinary voters think that it is never all right for journalists to use hidden microphones and cameras. On the other hand, among journalists a majority – 55% – thought it was all right in some cases. This was one of several ethical issues where Muller found a gulf between the attitudes of journalists and the public.

The bottom line is that most journalists regard themselves as perfectly adequate judges of where the public interest lies, and some are prepared to defy both ethical restrictions and even the law. It’s hard to defend such arrogance, particularly when notions of public interest so often accord with journalistic self-interest.

And yet the ethical issues aren’t simple. Remember the Age tapes affair in the 1980s? It was one of the stories of the decade, and it relied on the publication of illegally tape-recorded telephone conversations. Of course it was the police who did the taping, not the journalists, but as the fallout from the British scandal makes clear, it is common practice for reporters to use third parties to do their snooping for them.

Most journalists would say it’s fine to encourage a source to betray a confidence. Most journalists love whistleblowers, although whistleblowers often betray the trust of employers. Most journalists love to accept documents “off the back of a truck” even when they know they might have been obtained illegally. Without these practices, journalism would hardly exist. What is the moral difference between this and bugging someone?

The answer I think must lie in notions of privacy, which is a fundamental human right, and the opposite side of the disclosure coin. There are some circumstances in which citizens are entitled to believe that they are private. In their homes. In their private telephone calls. With their lovers. Any journalist who wants to invade privacy by effectively breaking into the house they are snooping around should have an overwhelmingly good reason for doing so. In the many cases of invasion of privacy in the history of Australian journalism, I can think of only one or two cases where the public interest has possibly justified the invasion.