Watching the US government’s case against Julian Assange is like watching a levitation act at the music hall. You can see that the object floats, but you’ve no idea how. If normal gravitational laws applied, the Assange case would have crashed to the ground already.

After all, a leading prosecution witness has admitted lying in his evidence to the court and the defendant and his lawyers have been spied on by the intelligence agency of the government attempting to extradite him. In any other case, the mere facts of these revelations would be enough to halt court proceedings, but the detail makes the case for abandonment of the extradition even more compelling.

The most recent bombshell is that Sigurdur ‘Siggi’ Thordarson has admitted to Icelandic journalists at Stundin that he lied when he gave evidence alleging that Julian Assange had instructed him to hack US government accounts. Thordarson’s evidence is not marginal to the US case: it’s woven all through the prosecution’s argument, and it is specifically referred to by the judge in the Westminster Magistrates’ Court in those parts of her judgement which are hostile to Assange.

Indeed, when the Trump administration realised that their case was weak, they specifically sought out Thordarson in Iceland and reissued their charges against Assange so that it would be, they imagined, strengthened by his evidence. They should have known better.

To say that Thordarson is an unreliable witness is a very considerable understatement. His allegations had been reviewed by the Obama administration and found too problematic to be taken seriously. Trump’s administration re-animated Thordarson in an attempt to breath life into their flagging case.

Thordason had been a volunteer for WikiLeaks, working to raise funds. He stole some $50,000 from WikiLeaks and he misrepresented himself to the outside world in order to embezzle money. He was also convicted of sexual abuse of children. On both counts, Julian Assange helped put him in jail. His motive for lying once again for the Trump administration is plain: revenge. And his false evidence is meant to bolster a central contention of the US case: that Julian Assange is a hacker, not a journalist.

Quite what has now convinced this serial liar to admit that he invented the material on which the US case so heavily relies we cannot know. But his decision to do so blows a hole through the centre of the case for extradition.

Thordarson admitted to the Stundin investigative team that Assange never asked him to hack anything. In fact, he now says that his previous claim that Assange had instructed or asked him to access computers is false.

Yet this is precisely the evidence on which the US prosecution relies. Indeed, it was so important to them that they tore up their original indictment of Assange on the very eve of the extradition hearing so that they could reissue a second indictment specifically including Thordarson’s evidence – evidence now admitted to be a total fiction.

At this point most cases which had been exposed as relying on perjured testimony would collapse. Not so the Assange case, which is now heading to the Appeal Court where the US will try to overturn the decision of the Magistrates’ Court at the start of this year, which found that the US prison system is so ‘oppressive’ that Assange would be a suicide risk were he committed to it.

It’s not even as if the Thordarson revelations are the first time that evidence has emerged which would normally halt court proceedings in their tracks. It is already a matter of record that Assange and his legal team were spied on by a Spanish security firm reporting to the CIA. The firm, UC Global, were employed by the Ecuadorean embassy to protect Assange when he was granted asylum. They were suborned by the CIA and then supplied them with both audio and video recordings of Assange and his legal team in the embassy. All this has been revealed in an ongoing court case in Spain.

Again, in any normal trial, the revelation that attorney-client privilege had been abused in this way would have been grounds for dismissal. But not in the Assange case. The court seems content to accept the US government’s argument that the CIA would respect departmental boundaries and never tell the Department of Justice any information obtained from the spying operation on Assange. This excuse beggars belief, since the exact function of the CIA is to tell the US government about the threats to national security, as they see it.

And there is the whole core of the problem: the US government under Trump allowed the fiction to develop that the fundamental business of investigative journalism is a threat to national security. Accordingly, Julian Assange became reclassified as a ‘cyber-terrorist’, not a journalist.

In pursuit of this dangerous fantasy, the US government is keeping a multiple award-winning journalist banged-up in a high security jail specifically used for terrorists, in spite of the Magistrates’ Court decision against them.

It’s time that both the US government and the British government brought this embarrassing farce to an end. Every major human rights organisation on the planet has said it is wrong. Journalists’ unions across the globe say its wrong. Parliamentarians in Italy are protesting in their legislature to says its wrong. German MPs are demanding Angela Merkel tells Joe Biden its wrong. Australian MPs are campaigning for Assange’s release in unprecedented numbers. British MPs have been protesting outside Belmarsh because they are not even being allowed a briefing with Assange.

As the Assange case goes to the High Court, we are reaching a critical moment. This is the crucial freedom of the press case of the twenty-first century. If it is lost, the shadow of authoritarian government will be cast longer and darker over the body politic. We should not allow that to happen.