Few moments have encapsulated the vast inequalities at the centre of the British media more than the assault on Carole Cadwalladr. A freelance features writer for the Observer, Carole got a whiff of a story about nefarious affairs in the Brexit campaign, and, for years after the vote, kept digging.

Around the same time, Peter Geoghegan and I started sniffing out a similar but different story, and also started digging. Our paths often crossed; we sometimes shared notes and pints.

Since then, Peter and I have moved on to other work. But Carole hasn’t been able to. One of the main subjects of both of our investigations, Arron Banks, has dragged her into court on the basis of something she said about him in a tweet, and in a Ted talk.

I won’t repeat what she said, because neither I nor openDemocracy want to end up in court too. The judge deciding Banks’s initial case against Carole found that the line had a specific meaning, and that – interpreted in that way – it wasn’t true.

But here’s the thing. Carole Cadwalladr uncovered lots and lots of things about very powerful people during her lengthy investigation into Brexit. Her reporting helped push both the Information Commissioner’s Office and the Electoral Commission to investigate the campaign group connected to Arron Banks – Leave.EU. They found it had breached various laws. She helped initiate a public debate about surveillance capitalism and the electoral process, and the power of big data companies and millionaires in our democracy – and what to do about it.

In the course of all that, she said something that I’m sure she believed at the time to be true, but which – if you think she meant what the judge says she meant – went beyond the copious evidence she’d gathered.

At that initial trial, the judge concluded that the statement was defamatory, but he found in Cadwalladr’s favour on the grounds that she was doing public interest journalism: so long as reporters do their very best to report the truth, so long as we’re working on subjects that the citizens of the country have a right to know about, we are allowed the occasional slip-up. Or so the first ruling said.

Banks went to the Court of Appeal, and here he got a different result. Carole will have to pay damages to Banks, and 60% of his costs – which adds up to more than £1m.

The implications of this for journalists are deeply worrying. The reality is that if Banks wasn’t very rich – if he was, say, the victim of some tabloid bullying campaign – then he wouldn’t have been able to sue. The Sun and the Daily Mail know fine well that they could, in theory, make up what they liked about ordinary people without facing serious consequences.

Secondly, Carole has been sued as an individual. Journalism is an increasingly precarious industry. Because investigations take time, effort and risk, newspapers are doing less and less of them. Much of the best work is done either by individual freelancers, like Carole, or smaller outfits, like us.

Organisations can spread out the risks of doing the work we do. But for individuals without the protection of collective endeavour, the risks of reporting on the super-rich will often just feel too high: one slip and they can bankrupt you.

That’s the message from the Court of Appeal this week, and it’s seriously dangerous for British journalism – and to British society as a whole.