As Donald Trump pointed straight at CNN’s Jim Acosta “You are fake news!”, the president refused to allow any further questions from the channel. The exchange left even the most seasoned journalists apparently boggling with disbelief. “Never seen anything like that, ever,” tweeted Mike Barbaro from the New York Times. This exchange took place on 11 January 2017, at Trump’s pre-inauguration press conference.

Ten days ago, after a battering for the Republicans in the midterm elections, the scene between Acosta and Trump was re-enacted, almost to the word. This time, in the grander setting of the White House, there was the added drama of a struggle for the microphone as a member of staff tried to remove it from Acosta’s hand. Again, the press had never seen anything like it. “This is something I’ve never seen since I started covering the White House in 1996,” tweeted New York Times correspondent Peter Baker. We are all seemingly careering around a Möbius strip of disbelief at the entirely predictable.

In professional wrestling there is a term “kayfabe” which relates to the performative rivalries that fuel the sport’s enormous popularity. It is often hard to tell in the ratings-fuelled grappling of Trump and the cable channels that cover him, where the “kayfabe” ends and reality begins. For Acosta, it ran into the hard reality of having his press credentials revoked by the security services, his press card taken away from him as he was walking between the White House and the CNN studio. The pantomime has consequences.

Given that the president is as obsessed with hard borders as he is with dissolving the boundaries of acceptable social and political norms, it is surprising that more press credentials have not been dramatically revoked in the past two years. Trump’s peremptory removal of a reporter’s credentials for attending a press conference has a precedent. In 1966 a writer for the Nation, Robert Sherrill, was denied press access to the White House by the secret service.

Described as “an ink-stained contrarian”, Sherrill was not in the mainstream of political reporting in the same way that Acosta is, but his case bears enough similarities to be cited in a legal suit filed against the White House by CNN.

Blow to Trump as judge restores White House access for CNN's Jim Acosta Read more

There was enough reason for a federal judge to agree with CNN on Friday morning and demand that the White House return the press credentials on the grounds that CNN would probably be successful in pursuing its case, although the suit will continue and the judge made no definitive ruling on the case.

It is surprising that more press credentials have not been revoked in the past two years

Although it took 10 years to finally settle Sherrill’s case, the ultimate finding was that he had both his first and fifth amendment rights violated (freedom of the press to operate without government interference, and the protection of due process and self-incrimination).

In other words, although reporters do not necessarily have a right to be allowed into White House press conferences, there must be good reason, and a proper appeals procedure, to deny access.

Testing Trump’s irrational actions with the law is important for the press, however. While the combative nature of his exchanges with journalists has been a high-rating distraction from issues that, according to the ballot box, people really care about, there is enough evidence now to be highly concerned both about press freedom and the role of political journalism.

Ahead of the midterm elections two shocking events took place against a background of highly charged rhetoric aimed at alarming voters. The first was a series of pipe bombs mailed to CNN, Democratic party politicians and the progressive philanthropist George Soros. The perpetrator, Cesar Sayoc, had a disturbing social media presence that featured many deranged far-right conspiracy theories, and mixed them with a fanatical love of Trump and a credulous adherence to the outpourings of Fox News.

The second was the fatal mass shooting of 11 people at a Pittsburgh synagogue by a gunman who had expressed, again on social media, antisemitic paranoia about refugees. This baiting of the paranoid and vulnerable, to a point of violent radicalisation, has happened through the vectors of Trump’s rhetoric and the interplay between mainstream media and the social web, fuelled largely by Rupert Murdoch’s Fox News. In parts of its schedule, it has given up any pretence of trying to examine the news of the day from a rightwing perspective and has, instead, published political narratives for Trump much as any propaganda or political lobbying group might.

Ironically, the series of questions that Acosta was asking the president when he was smacked down revolved around the story of a movement of a small number of people from central America to the US border seeking asylum. The “migrant caravan” started as a theme as long ago as March, but cropped up increasingly frequently as the midterm elections approached.

Fox News, which is enjoying historically high ratings, was the critical outlet for turning a phoney talking point for the president into a “news” item, which far too many other news outlets followed.

In the days running up to the election, Fox plastered its talkshows and prime-time news with mentions of the migrant caravan.

Fox & Friends, Trump’s favourite news show, mentioned the story 38 times in the three shows ahead of the midterms, and only once on the morning after, despite having a reporter “embedded” with the group. Its most popular financial anchor, Lou Dobbs, tweeted a poll to his 1.85 million followers asking if they believed the caravan was secretly funded by radical leftists.

The dog whistles that encourage the demonisation of figures such as Soros, the underwritten messages of antisemitism and racism, show up unchecked in the social feeds of the bot and real followers of the president.

There are few more reliable indicators of what Trump’s White House will feature as its next talking point than Fox News talkshows. Yet in the wake of the midterm elections there have been some surprising movements here, too. Last week it joined CNN’s legal challenge against Acosta’s ban. The channel’s Twitter feed, with 18.5 million followers, fell silent apparently in protest at Twitter’s failure to act promptly on shutting down the “doxxing” (the release of his home address) of the Fox host Tucker Carlson.

These moves are somewhat puzzling to close observers of the channel and its place in honing and promoting the Trump agenda. Many more progressive journalists were wondering why their own corporate Twitter feeds had not staged similar social media strikes in the face of online harassment or abuse.

The joining of a legal challenge with CNN might signal that the channel is imagining it might find itself in a similar situation once the current administration runs its course. Or it could be the beginning of a subtle shift in body language that tries to separate its corporate behaviour from the “free speech” of its shows. The Acosta case in one way is a continuation of business as usual in a phoney war between the president and the press, but it should mark a turning point.