Until the moment Fairfax Media and The Huffington Post hit the publish button at 10pm on Wednesday, AEDT, revealing how the oil industry really works, our investigative team was on tenterhooks.

This was more than simple pre-publication nerves, the questions we invariably ask ourselves about whether we have got it right, and what we had missed in the hundreds of thousands of documents we'd read over the previous months.

No, our concern was more specific: that an Australian court, an unsympathetic judge, might stop us publishing this global story. It would have left The Age and The Sydney Morning Herald newspapers with seven blank pages each, and thousands of words of crucial information unable to be published online.

It may have meant a story that Fairfax Media's reporters had worked on solidly for months would be broken overseas by our collaborator, The Huffington Post, not by the reporters who sourced, corroborated, combed and read hundreds of thousands of emails.

This was no idle concern. The day before publication, Unaoil had sent a threatening legal letter reserving their right to seek an injunction in Australia's courts.

Unaoil's legal letter

"Our clients have recently become aware that two Fairfax journalists ... have been contacting clients and persons associated or formerly associated with the Unaoil Group and requesting information regarding ... alleged corruption and bribery of foreign officials," said the legal letter from Sydney firm Kennedys, received on Tuesday afternoon.

"The allegations are extremely serious and highly defamatory. Our clients strenuously deny any wrongdoing and consider the allegations to be baseless and entirely false."

Unaoil and its family owners, the Monaco-based Ahsani clan, knew we intended to write about them because more than a week earlier we had told them so. Reporters Richard Baker and Nick McKenzie had called patriarch Ata Ahsani, his son Cyrus and and their Iraqi fixer, Basil Al Jarah.

A series of conversations with their public relations representative followed, and then the team sent a detailed list of questions – 27 in all – via email.

This is normal journalistic practice: to give the subject of a story a reasonable right of reply prior to publication. But it also raised the possibility that the multimillionaires who ran an operation to systematise the corruption of the oil industry would use the courts to stop us.

The ground they relied upon was that we had what they considered their property – the hundreds of thousands of emails leaked to McKenzie. Though we had not told them we had the emails, nor how we came by them, Unaoil clearly believed we were working from "stolen" material.

The letter said: "We ... request your urgent response to the following matters:

"(a) Has Fairfax or any of its journalists seen, come into possession of, or been provided with, any documents or information that were unlawfully obtained or removed from our clients' files, electronic archives or email servers?

"(b) Has Fairfax or any of its journalists communicated with any person, including any former employee of the Unaoil Group or its related entities, who has disclosed the contents of any documents or information described ... above?"

Unaoil wanted all copies of any emails removed and all electronic versions destroyed, and that Fairfax "desist from publishing any material" until the company had "been able to verify that their confidential data is not being used to make scandalous and defamatory allegations".

Our response? That this was a story that was manifestly true, and clearly in the public interest, and we were not going to allow a corrupt company protecting its paltry reputation to stop us.

By the way, Unaoil has still made no attempt to actually answer our 27 questions. Nor have they suggested that the emails and documents we've relied upon are anything but authentic.

The cache of emails we had obtained made a mockery of all the pious claptrap that companies such as Unaoil and many of their clients come out with about acting ethically and complying with anti-corruption laws. The story opens a window on how the West really treats the East. Not to publish would have been unethical.

Now that we have, the world is watching. Just 12 hours after it was published, almost 500,000 people had clicked on the Fairfax site devoted to it. It will be one of our most read stories this year. The Huffington Post, our collaborator, took millions more.

The story was picked up on Huffington Post sites around the world, other aggregator sites such as Salon.com, where Unaoil was described as "the most important company you've never heard of", and the Daily Mail.

Mark Ruffalo, the actor and activist, tweeted the Huffington Post version of McKenzie's story under the headline "Spotlighted!"

Wikileaks retweeted us.

But the more important reaction may come in the next days, when the world absorbs the revelations: when the protesters surrounding the Green Zone in Baghdad realise that one of the ministers they are targeting was deep in the pockets of Unaoil; and when politicians and police in Australia and abroad ponder whether to stand by in the face of such evidence of corruption.