In exposing what he called an extortionate proposal from the US publication National Enquirer, Jeff Bezos, founder of Amazon, concentrated minds in newsrooms last month when he wrote in a blogpost: “Be assured, no real journalists ever propose anything like what is happening here.”

The Enquirer’s proposal, in emails Bezos disclosed, was that if Bezos would state publicly that there was no basis for suggesting the Enquirer’s coverage was politically motivated or influenced by political forces, the Enquirer would stop publishing intensely private communications between Bezos and a woman with whom he was in a relationship.

Trump, 'blackmail' and a Pecker: Bezos delivers scandal with something for everyone Read more

As Bezos put it, federal investigators and the press had proved that the Enquirer was used for political reasons. So, as Bezos saw it, he was being asked to lie in return for his personal communications being kept confidential, although the Enquirer would retain them for potential future use if he deviated.

“Of course I don’t want personal photos published, but I also won’t participate in their well-known practice of blackmail, political favors, political attacks, and corruption,” Bezos wrote. “I prefer to stand up, roll this log over, and see what crawls out.” The Enquirer’s parent company has denied acting unlawfully.

Other logs have rolled in the past, and what emerged gives context to the Bezos experience and assurance.

I do not want to be misunderstood as suggesting the worst practices are rife. But they are not unknown. Journalists make arrangements with sources all the time, within a range that begins at proper and benign, travels through occasional back-scratching to mutual dependence, and may shade into unethical or even unlawful.

About 10 years ago, large-scale phone hacking by the UK media was revealed. Reporting, litigation and a public inquiry have shed light on tactical approaches similar to the one Bezos alleges has been tried on him.

Here is counsel questioning an editor about his reporter’s threat to publicise the identities of two dominatrices unless they agreed to his paper’s plans for further coverage of their well-known client’s sexual proclivities, in which case they could stay anonymous and receive money from the paper:

Q What’s it called when you threaten to reveal publicly the identity of somebody who has done something embarrassing which they do not wish to become public unless they cooperate with you?

A I think you know what it’s called. You’re talking about the potential use of blackmail.

The reporter, under cross-examination, seemed so inured – blackmail never crossed his mind, he said, “I’m offering them a choice” – the judge commented that the reporter “genuinely did not see the point. Yet it is elementary that blackmail can be committed by the threat to do something which would not, in itself, be unlawful.”

In a different case, an email emerged in which two editors shared concern about a reporter who had sought police cooperation to obtain an exclusive:

“Fantastic world exclusive from [reporter’s first name] … But … there are some issues about exactly how his relationship with [police force name] developed. Things got VERY heated … when they took exception to a … piece which accused them of seeking maximum publicity, and said they’d have to answer for their actions … In a series of angry conversations … [police] ended up accusing [reporter] of blackmail. (Yes they used the word blackmail.) They said he came to them with loads of detail on their investigation and they felt their only course of action to protect their inquiry was to cooperate totally with him.

“This suggests to me extreme naivete on their part. But it also suggests (and [reporter] doesn’t entirely deny this) a rather heavy-handed approach by him. He seems to have been nailing them to a wall, saying if they didn’t give him a guarantee of an exclusive tip off on the search operation, he’d broadcast a story in advance. (Which of course we would never have done.) One part of me is hugely impressed with his tactics. But it wouldn’t look pretty if it came out – and it nearly did yesterday … Anyway, the point of this long email is to warn you that [reporter has] had both a very successful and very bruising time, and … we’ll need to talk through with him what’s okay and what’s not in getting exclusives.”

The judge found the editor’s explanation of his email “unconvincing”.

In his robust book Hack Attack (Chatto & Windus, 2014), Nick Davies, the journalist who did much to expose through the Guardian the Fleet Street scandal, points to a serious effect of these tactics: their potential to distort secretly the exercise of public power, not through disclosure, but rather through withholding.

Jeff Bezos accuses National Enquirer owner of 'extortion and blackmail' Read more

A US lawyer said the Bezos case “shows how frightening it should be to the citizens of the US that the National Enquirer reportedly has a safe full of information about the president … That’s one of the dangers to democracy of what they were engaged in when they were catching and killing information they could have used against candidate Trump and now President Trump … It’s a shocking and frightening thing Mr Bezos has revealed.”

Reminders about the potential for abuse of media power, and of its exposure by journalists, are always valuable.

• Paul Chadwick is the Guardian’s readers’ editor