When Bradley Manning's defense attorneys wanted someone to explain journalism (pdf) to the court (pdf) trying him, they did not call on a journalist, they called on a legal scholar and expert in networks: Yochai Benkler, co-director of the Berkman Center for Internet and Society at Harvard and author of The Wealth of Networks.

For as Benkler explained to the court, journalism is now a network – a "network 'fourth estate'".

In this network, there are many roles that can be linked together: witnessing, gathering, selecting, authenticating, explaining, distributing. Each can be an act of journalism. Each can be done by someone else, not necessarily working in a single institution. "Journalism," said Benkler, "is made up of many things."

Those actors can now include not just the reporters and editors in newspapers, and not just bloggers working alone, but also other, new players: witnesses who share what they see on the streets of Cairo, Rio, or Istanbul; witnesses or whistleblowers who share what they discover in their work (see: Manning or Edward Snowden) and organizations that aid one function or another (see: WikiLeaks). As Benkler went on to testify Wednesday:

One of the things that's happened is people realize that you can't have all the smartest people and all the resources working in the same organization. So we have seen a much greater distribution in networks that even though they use the internet, what's important about the network structure is actually permissions, who's allowed to work on what resource or assignments of work assignments.

Permission is precisely what is at stake in Manning's trial and will be if Snowden is brought to court: both men had permission to see what they saw. They did not have permission to share it. Or if they are deemed whistleblowers, do they? Well, that may depend on whom they shared their information with: a journalistic organization, perhaps. But is WikiLeaks such an organization? Or is it a source for "the enemy"?

That is an issue Benkler and attorneys wrestled with, as he argued that WikiLeaks was indeed seen as a journalistic organization – until Manning's files became public (with the help of the Guardian, the New York Times, Der Spiegel, el Pais and other clearly journalistic enterprises). From then on, Benkler said, WikiLeaks was demonized by American politicians in their "shrill" campaign against it. To use Benkler's word, WikiLeaks was "delegitimized". Its permissions were withdrawn.

All this matters to Manning's defense because it informs the question of intent: did he intend to share the videos and files he found with fellow citizens or with the enemy? Was WikiLeaks a journalistic entity with links to the public or an enemy tool with a line to Bin Laden?

The exact same question is already raised about Snowden: did he intend to share with the public through this newspaper or with other governments in their airports? There lies a line between whistleblower and spy – or so the argument goes.

There's another issue in play: the one around "a journalist". Who is a journalist? For that matter, what is journalism? Those questions underpinned not only Benkler's testimony, but also the debate buzzing around the head of the Guardian's Glenn Greenwald, as some colleagues in the field have amazingly questioned his role (his permission), and thus whether he should be arrested for aiding and abetting a criminal suspect.

They do that because Greenwald is an advocate and a journalist; while journalists – in the US, at least – have long believed that one must be a journalist or an advocate. Benkler told the court that one can be both. I argue that all journalism is advocacy even if it is simply advocating for openness and transparency, or standing up for the downtrodden, or believing that the public must be better informed.

New York Times public editor Margaret Sullivan tried recently (and for what must be the millionth time) to define a journalist. Senator Dick Durbin has proposed that the government should define who is a journalist.

But that would be tantamount to licensing the journalist. That is a permission government should not grant, for that gives government the power to rescind it.

Here's the problem – the problem Benkler presents in his testimony: in a network, anyone can perform an act of journalism. Thus, I argue, there are no journalists. There is only the service of journalism.

At the Guardian's Activate conference in London, this Tuesday, I asked Vint Cerf, a father of the internet, about the notion that journalists still think they manufacture a product called content (a noun) while Cerf's invention and his current employer, Google, concentrate on making verbs: services that perform a function for people or society. Surely, as I've argued on my blog recently, journalism is such a service.

Journalism is not content. It need not be a profession or an industry. It is not the province of a guild. It is not a scarcity to be controlled. It no longer happens just in newsrooms. It is no longer confined to narrative form.

So, then, what the hell is journalism?

It is a service whose end is an informed public. For my entrepreneurial journalism students, I provide a broad umbrella of a definition: journalism helps communities organize their knowledge so they can better organize themselves.

So, anything that reliably serves the end of an informed community is journalism. Anyone can help do that. The true journalist should want anyone to join the task.

That's not a complicated definition, but it raises no end of complications, especially in a set of laws that is built for institutions, not networks. What if Manning, WikiLeaks, Snowden and Greenwald all performed acts of journalism? I say they have, for they performed services in the name of an informed public. There is a role for the witness, the whistleblower, and the advocate in the "network fourth estate".

And there must still be a role for journalistic institutions. For it is they that have the resources to perform many of the necessary functions that come after witnessing: selecting, authenticating, explaining, distributing. And it is they and their lawyers who can withstand the pressure that governments will put on them – witness the trial of Manning and the pursuit of Snowden – to forbid transparency.

In his testimony, Benkler warned the court of the precedents that may set: