Since 1803, when its first newspaper was published, Australia’s media have been owned largely by private enterprise. Except for the Government Gazette, which was confined to publishing official government notices, newspapers were all privately owned. This remains the situation today.

Commercial media have been integral to Australia’s political, economic and social development. Some have not always been especially edifying – the Sydney Monitor specialised in gruesome accounts of public floggings. But others have been conspicuously high-minded, at least in their aspirations. The Sydney Morning Herald declared on its masthead:

Sworn to no master, of no sect am I.

Not that it came close to living up to its promise. As Gavin Souter wrote in the Herald’s official history:

It was against emancipists, penal reformers, Catholics and Blacks.

In privately owned media organisations, choice of news (a preference for gruesome accounts of floggings) and choice of opinion (that penal reform is undesirable) are the prerogatives of the proprietor.

Choice of news is generally made on the basis that the stories chosen will appeal to the newspaper’s readership and will therefore continue to deliver to advertisers the audience that the advertiser has come to expect. There is nothing wrong with this, and it happens that a large amount of news is both important to the functioning of a liberal democracy and of genuine interest to audiences.

Take the recent revelations by the ABC and The Guardian Australia about Australian spying on Indonesian President Susilo Bambang Yudhoyono, his wife and his cabinet ministers. This was a story of wide appeal – a glimpse into the secret world of spies, acute government embarrassment, a huge row with Australia’s biggest neighbour, and a raging political controversy.

It was also a story that raised questions of substantial public interest. In the post–September 11 world, have the intelligence agencies been given too much latitude, who is meant to be monitoring them, and is the monitoring effective?

In publishing this material and raising these question, the two outlets were performing what is called the “fourth estate” function of the media – being a watchdog on others in power. Not everyone agreed that they were ethically justified in publishing this material, arguing that the harm done outweighed the good, but the ethical arguments in favour of publishing were likewise compelling.

Here, the choice of news was shared by a private enterprise outlet – The Guardian Australia – and a publicly funded outlet – the ABC. It is a good example of how genuinely important news transcends the economics of media. In fact, many large and important stories published by private media in Australia have been published not because they attract readers or advertising but because they are important.

The pursuit of the Howard government over the persecution of Dr Mohamed Haneef, and the exposure of alleged corruption in a subsidiary company of the Reserve Bank are examples of stories that are expensive to gather yet are unlikely to add anything to sales. The same could be said for the revelations of endemic corruption in Queensland by ABC television’s Four Corners in its program The Moonlight State.

So in news coverage, Australia has been well served on the whole by its privately and publicly owned media.

However, choice of news is only one of the proprietorial prerogatives referred to earlier. The other is choice of opinion, and it is here that differences between privately and publicly owned media have their roots.

The ABC is required by law to provide an impartial news service. This means that the ABC does not have a corporate opinion on matters in the news. It publishes other people’s opinions, including the opinions of its individual staff. Some critics of the ABC say that this is a Jesuitical distinction: that the ABC publishes the opinions that suit its own world view and in this way promotes its own view.

Even if there were any merit in that argument – and there is scant evidence to support it – such second-hand and diffuse opinion is not qualitatively comparable to the opinion directed first-hand by a newspaper proprietor or the editors to whom he delegates this function.

This isn’t just code for Rupert Murdoch. Rupert’s father Sir Keith (though more in the role of managing director than owner), Kerry Packer, his father Frank, Sir Warwick Fairfax and his forebears going back to the early 19th century: all of them used their newspapers to promote their opinions and preferences.

While these preferences were sometimes governed by ideology, they were very often governed by commercial considerations. Nowhere was this clearer than in the pressure Kerry Packer and Rupert Murdoch exerted on the Hawke and Keating governments over media ownership policy.

Australia now exists in a world where media technologies have converged in such a way that newspaper publishers broadcast audio and video as well as print newspapers, and broadcasters publish text as well as transmit radio and television programs.

At the same time, there is very little diversity of voice. Most privately owned media are in the hands of two big newspaper companies (News Corp and Fairfax), the commercial television companies and a couple of radio conglomerates.

In this converged and concentrated environment, the ABC adds a voice: a trusted voice.

An analysis of public attitudes to the media over 61 years from 1950 to 2011 shows that the ABC is by far the most trusted media organisation in the country. Where other media organisations struggle to get even half the people to say they trust them, the ABC consistently has anything from two-thirds to four-fifths of people saying they trust it as a source of news and information.

Over the decades, newspapers have been plagued by comparatively low levels of trust. The exact reasons for this remain a matter of speculation, but it is possibly linked to an enduring public perception that newspapers are more biased than television or radio. The possible link between trust and bias is reinforced by the fact that the ABC is perceived to be the least biased media organisation in Australia.

Because of technological convergence, however, the ABC is now in direct competition with the privately owned media in a much more comprehensive way than ever before. Murdoch’s News Corp takes particular exception to this, and has been running an aggressive campaign against the ABC, attempting to create a climate in which the ABC is seen as an unnecessary drain on the public purse and an encroacher on private commercial territory.

History tells us that while Murdoch has not been very successful in getting politicians to adopt his policy preferences generally, he has been very successful in getting them to do what he wants in the field of media policy specifically. For that reason, his campaign against the ABC is a matter of substantial public interest and calls for continual scrutiny.

Denis Muller is Senior Research Fellow in the Centre for Advancing Journalism at the University of Melbourne.

This article was first published at The Conversation.