Imagine being picked up by the police, taken to a maximum security prison, and held for years – indefinitely, for all you know – without being told what it is that you’re supposed to have done. Sounds familiar? If you substitute “soldiers” for “the police,” it sounds like Guantánamo, or Bagram, or Abu Ghraib. But it’s not. It’s Belmarsh prison, in south east London.

Three years ago, in December 2004, after 17 men, captured and held as described above, had already been imprisoned in Belmarsh for at least three years without charge and without the prospect of a trial, Britain’s law lords ruled that this kind of detention was in breach of human rights law. In response, the government introduced a new form of detention without charge or trial. Under the control orders introduced in spring 2005, the eleven Belmarsh prisoners who were still in detention were allowed to return home, but were subjected to a range of measures which severely restricted their liberty.

In some obvious senses, this new regime was less brutal, although it was no less unjust. As the released Guantánamo detainee Moazzam Begg reported in the Guardian, the control orders “consisted of a panoply of measures restricting the movement of the men as well as their ability to communicate with the outside world, and included home curfews, remaining within the confines of a specified radius, the approval of telephone calls, a ban on mobile phones, internet access and unauthorised visitors; the wearing of an electronic tracking tag, signing-in up to four times a day at a police station and calling security firms several times a day.” Noting that the impact of control orders on these men’s mental health, and on their wives and children, has often been “intolerable,” he added, “Though few have said it, ‘house arrest’ is the term that comes to mind.”

This was something of an understatement. If Belmarsh (where some of the original prisoners were once more incarcerated, after being rearrested following the London bombings in July 2005) was this government’s shameful reinvention of the reviled policy of internment, as practiced in Northern Ireland, to disastrous effect, in the 1970s and ‘80s, the control orders (which were subsequently extended to include British nationals and a new wave of uncharged undesirables) are indeed a form of house arrest.

On Wednesday, the law lords, having reviewed the control orders in the light of three separate challenges to their legality, delivered another verdict, which, unfortunately, was but a toothless shadow of the righteous indignation that they had unleashed on the government three years before. Tinkering with the system, they ruled, in the case of six Iraqis, that an 18-hour home curfew was in breach of the right to liberty, as guaranteed by the European convention on human rights, and, moreover, ruled that the system of secret evidence must be changed to let the suspects know the case against them, and to give them the right to a fair hearing (a verdict which should have been on the front pages of newspapers, although it was not). Noticeably, however, they failed to rule that the whole experiment was as vile and illegal as its predecessor, heaping shame upon England’s proud reputation as the home of habeas corpus.

Although the law lords argued that they were, in fact, upholding the suspects’ habeas rights by ruling against the government’s reliance on secret evidence and its insistence that it can restrict the liberty of these men without ever charging them (Lord Brown, memorably, said that the right to a fair hearing was “one of altogether too great importance to be sacrificed on the altar of terrorism control”), it remains apparent that, by refusing to condemn the control orders outright, they have perpetuated a brazenly draconian system, which appears, dangerously, to be fuelled by anti-Muslim vindictiveness, even though the more prosaic truth is that it is driven by an anachronistic refusal to “compromise the security services” by proceeding with trials using intercept evidence (despite the fact that most other western democracies have managed to do so without imperiling their “spooks”).

The importance of the dispute over the control orders’ legitimacy was clearly recognized by the lords. In addition to Lord Brown’s comments, Lord Hoffman declared, “Such is the revulsion against detention without charge or trial, such is this country's attachment to habeas corpus, that the right to liberty ordinarily trumps even the interests of national security,” adding that such rights were simply “too precious to be sacrificed for any reason other than to safeguard the survival of the state.” As the Economist reported, however, “even he had doubts” as to whether the control orders “amounted to an unlawful deprivation of a fundamental human right or a simple restriction upon [the suspects’] liberty. Whereas continuous house arrest was clearly equivalent to imprisonment or detention, he was not so sure about the imposition of an 18-hour curfew. There was, he suggested, no clear dividing line between what was acceptable and what was not.”

Lords Hoffman and Brown and their colleagues are to be congratulated for insisting, as the Economist described it, “on a suspect's right to see the key evidence against him, even if disclosing it is deemed contrary to national security interests,” but in their dithering over the bigger picture they have overlooked one crucial fact, established with alarming clarity over the last six years: that allowing governments to imprison people without charge – even if theoretically justifiable, in a few extraordinary cases – relies upon a stout belief that the government’s “secret evidence” is reliable.

Time and again, however, the intelligence services have been shown to be woefully lacking in reliable evidence. Of the 30 control order cases introduced in the last two and a half years, seven have been dismissed on appeal, and credible doubts have been expressed about the nature of the secret evidence against many of the others. In April 2005, for example, the Home Office was forced to apologize to ten of the men under control orders after what it described as a “clerical error,” which resulted in letters being sent to them stating, incorrectly, that the basis for their detention was their alleged involvement in the so-called ricin plot, and in January 2005 an extraordinary list of intelligence blunders relating to the Belmarsh prisoners was published in the Independent.

In an article entitled, “Belmarsh detainees: Flawed intelligence exposes scandal,” Robert Verkaik, the Independent’s legal affairs correspondent, noted, amongst other errors, that “A security service assessment was embarrassingly withdrawn after it emerged that the purpose behind a visit to Dorset by a group of Muslim men had not been to elect a terrorist leader but to get away from their wives for the weekend,” that “The Home Secretary has been forced to concede that some of the funds raised by the detainee Abu Rideh for alleged terrorist activity were sent to orphanages in Afghanistan run by a Canadian priest,” that “Two of the detainees were awarded compensation for false arrest shortly before they were detained under the anti-terrorist emergency powers,” and that “Testimony against two of the detainees came from an affidavit sworn by a man who was offered a lenient sentence in return for evidence.” In conclusion, Verkaik observed, justifiably, that, although these mistakes were based on the “open” evidence against the suspects, “the inaccuracy of some of these assertions raises questions about the reliability of the secret evidence that the detainees have never been allowed to see.”

As Guantánamo and the secret prison network run by the Americans have shown (and as I describe in detail in my newly released book The Guantánamo Files: The Stories of the 774 Detainees in America's Illegal Prison), allowing the intelligence services to operate without any legal oversight, and resorting to secret evidence, which may be based on torture, coercion or hearsay, is no way to ensure that justice is served. The fog of secrecy surrounding Belmarsh and the control order suspects is no less damaging. The law lords took one step in the right direction on Wednesday, but house arrest, however, mitigated, still has no place in a civilized society. If there is a case to be made against any of these men, it should, as with the “enemy combatants” held by the US administration, take place in a courtroom.