Powerful figures are increasingly suing media outlets before they have even published a story, the editor of the Wall Street Journal has said.

Emma Tucker, whose title is being sued by Donald Trump over its reporting of his relationship with the late child sex offender Jeffrey Epstein, said the act of reporting itself was now under threat from the use of lawfare.

She said the tactic of suing newspapers before they had published a story had become an established PR strategy of the powerful amid greater distrust of the established media.

“One of the biggest challenges to us now isn’t so much what happens afterwards,” Tucker told the Harry Evans investigative journalism summit, named after the former Sunday Times editor. “It’s what happens before you even publish. That is a massive challenge for us.

“Increasingly it is the case that before you even get to publication, lawsuits come raining down on you – a whole torrent of legal letters come your way. Deep-pocketed people [are] doing this as a PR strategy, because then other journalists then write up ‘look, so-and-so is suing the Wall Street Journal for some reporting that they’re doing’.”

She added: “The Trump story [about his alleged letter to Epstein] epitomised how difficult and expensive these stories are. But at least the defamation came after we’d published. These days, increasingly, we’re getting legally challenged before we even get to publication.”

Tucker was speaking on a panel discussing the growing pressure on investigative journalism that is spanning both authoritarian and democratic states.

The World Press Freedom Index, compiled by Reporters Without Borders (RSF), for the first time placed more than half of all countries in the “difficult” or “very serious” categories for press freedom.

It found that while in 2002 a fifth of the global population lived in a country where press freedom was categorised as “good”, that had now fallen to less than 1% of the world’s population.

Patrick Radden Keefe, the investigative journalist who uncovered the role of the Sackler family in the US opioid crisis, told the summit that there was now tension over reporting on Trump’s White House.

Radden Keefe said the administration was challenging objective truth but was also “good for business” for media companies.

He pointed to the White House Correspondents’ Association dinner, which he said had become a “kind of a parody” as journalists denounced it while insisting they had to attend.

“Part of what we should acknowledge is that Trump has in some respects been very good for business, that these enterprises which are in the business of getting clicks and selling subscriptions and so on and so forth have found that the Trump administration makes great copy,” he said.

“On the one hand you want to hold power to account and on the other hand this is the most entertaining show on earth. This is a reality TV presidency that has turned politics into entertainment by other means … I don’t know that there’s any news organisation that has figured out how to thread that needle.”

Kath Viner, the Guardian’s editor-in-chief, who was also on the panel, said the challenge posed by AI and political hostility to reporting meant “reality itself feels fake”.

She said: “That has big challenges for news organisations. But it also does have big opportunities because if we stay committed to the truth and not fall into the trap of AI slop, then I think we can differentiate ourselves and show our value.”

In a speech published on Wednesday, Viner said “transparently funded journalism in the public interest” had to be part of the solution.