Those liable to abuse public office are great believers in the fog of history.

Again and again they persuade themselves that it covers every track, obscures every question and gives cover to anyone with a need to stay out of sight. What we don't know, runs the eternal thesis of secret government, won't hurt us.

They are half right. The case of Pat Finucane alone – there are plenty of others – is proof that no conspiracy is perfect. The truth comes out, sooner or later, even if justice is hellishly slow to follow. The fact remains that it is almost as hard to set the past to rights as it is to make restitution. Worse, the lovers of the cover-up never learn.

Sami al-Saadi, his wife and four children, have just received £2.23 million of taxpayers' money in recognition of suffering endured. Britain's Government has made the payment in compensation, but without – follow the logic, if you can – accepting liability. Rather than interpret this humiliation as a reason to establish the truth, finally, about Britain's participation in the black arts of rendition, ministers are working to find new ways to keep cases quiet. In secret, for preference.

Mr al-Saadi is not, and was not, one of your standard-issue caricatures of an Islamist. Instead, his mistake was to oppose the regime of Colonel Muammar Gaddafi when London and Washington were still cultivating the Libyan dictator, mostly thanks to Tony Blair's infamous "deal in the desert".

Mr al-Saadi spent years dodging the regime's agents. Finally, in what is a described as "a joint UK-US-Libyan operation", he was bundled onto a plane in Hong Kong with his family, flown to Tripoli, and imprisoned. Mr al-Saadi was then tortured, regularly and routinely, for years on end. In certain offices in London, this was a cause for celebration.

We know this because of documents brought to light after Col Gaddafi was bombed from power by Britain and France in 2011. Affectionate notes from the CIA to Moussa Koussa, the former Libyan intelligence boss who "defected" to Britain before being allowed to go on his merry way, were found by Human Rights Watch. One said: "We are- aware that your service had been co-operating with the British to effect his (Saadi's) removal to Tripoli - the Hong Kong government may be able to co-ordinate with you to render (Mr al-Saadi) and his family into your custody".

Such had been an element, it seems, of Mr Blair's 2004 deal. Did we care whether these "enemies of the regime" were innocent or guilty? Abdel Hakim Belhaj, still embroiled in legal action against our Government, was rendered with his pregnant wife. Sir Mark Allen, MI6 head of counter-terrorism, wrote to Mr Koussa to offer congratulations, and state: "This was the least we could do for you and for Libya. I know I did not pay for the air cargo (but) the intelligence ... was British".

The use of pronouns is fascinating. It counts, if nothing else, as a handy definition of Not in My Name. But facts are facts. Mr al-Saadi has been paid off simply to avert a trial in a British court. The rule of law, foundation of the democracy defended against terrorism, has been circumvented because a trial would, supposedly, imperil that democracy's security.

Britain's involvement in rendition and torture is denied but also, on the evidence, beyond doubt. As a string of cases across Europe has shown, at least 14 governments were – or rather are – implicated in the CIA's global kidnapping schemes. Simple mistakes and calculated brutality have been rife. The American legal system, right up to the Supreme Court, refuses to concern itself. And Britain pays off the victims it can't ignore.

Having relieved the Daily Mirror of £54,650 for libelling him as a "racist comedian", the stand-up Frankie Boyle has joined the charity Reprieve in helping Shaker Aamer launch a defamation action against MI5 and MI6. Mr Aamer was put away in Guantanamo over a decade ago. He is the last of those whom Barack Obama failed to free with a claim, as a British resident, on our Government's protection. And most of us have never heard of him.

Mr Aamer alleges, chiefly, that the intelligence services have lied about him by telling the CIA he is "linked" to al Qaeda. His lawyers have written to William Hague, Foreign Secretary, and to Theresa May, Home Secretary, demanding an explanation. The lawyers also want the Government to explain why indefinite detention is not a war crime in British law. The Metropolitan police – don't all cheer at once – are investigating.

The prisoner has been inside America's extra-territorial facility since 2002, but no trial is proposed. For that matter, no charges have been laid against Mr Aamer. Even if the spooks were right, even if the claims that he – in his lawyers' rebuttal – got involved with mosques serving as an "attack planning and propaganda production base for al Qaeda" are true, where's the trial? Why, time and again, are trials deemed impossible in a country defending the rule of law?

Here things become opaque. Tory ministers in the Coalition serve up convoluted arguments to justify "close material proceedings" – secret civil trials – not to establish the truth, but to end embarrassing pay-outs to the likes of Mr al-Saadi. The Lords have already rejected several aspects of Ken Clarke's Justice and Security Bill, but David Cameron, like his minister without portfolio, is not giving up.

On Tuesday, the Prime Minister handed the Commons liaison committee a rhetorical question in place of an explanation. "What would you do about the fact that we are having to pay out money, often to unsavoury people, who might have made bogus allegations against Britain and we have no method of hearing those cases in court?"

"Might" is the interesting word. We "have no method", meanwhile, because the Government has no taste – because America might not like it – for proceedings in an open court. As Mr Clarke put it in the Huffington Post last month, the problem "centres on the highly unsatisfactory rules which currently prevent British judges from taking sensitive national security evidence into account when deciding a case. This makes it impossible for them to untangle the claims and counter-claims about alleged British involvement in the mistreatment of detainees".

And who makes these unsatisfactory rules? This is circular logic. It ends with, under Mr Clarke's proposals, secret trials in which defendants (or claimants) would not be allowed to be present. They would not be entitled to know or even challenge the case against them. And they would be represented, like it or not, by a Government-selected ("security-cleared") advocate, not their own lawyers.

England's Law Society is outraged. Shami Chakrabarti, director of Liberty, points out time and again that the Government cannot identify a single case in which judges have forced "the exposure of state secrets". Clare Algar, for Reprieve, puts her finger on the actual motive. The Government "has settled cases because there has been clear evidence they were mixed up in serious human rights abuses".

When the fog clears, such things must surely merit a trial in plain view. Instead, Government and law alike have been corrupted by the imperatives of a war on terror that long lost whatever point it was supposed to possess. If justice "seen to be done" is forfeit, the most important battle is lost.