The Guantanamo prisoners will now be charged with the retrospective crime of belonging to the Taliban, a legal device that was not even used against the Nazis at Nuremberg

What a shambles "homeland security" is becoming here. If you mention the former Pennsylvania governor Tom Ridge, brought in by President Bush to oversee domestic security, you are greeted with apologias: decent fellow but not a natural communicator, no real staff, no big budget, no real power - and that last criticism, in a city crazed with power, is the real killer. In poor Ridge's new "colour codes", designed to tell us how much danger we are in, we are currently at yellow - the middle level allocated to an "elevated" risk (while green is "low", blue "guarded", orange "high" and red "severe", ie, under attack). Nobody takes the colour codes seriously, especially because, in US hospitals, blue means that the patient is dying.

The Bush administration is thus digging itself deeper into numerous holes, with an incoherent Middle East policy and a team riddled by internecine warfare. Someone - the CIA? - recently tried to put the knife into General Tommy Franks (and, by implication, Donald Rumsfeld) for managing to lose Osama Bin Laden. Having brought in a wave of post-constitutional, overkill measures in the wake of 11 September, the Bush team doesn't quite know what to do next.

Take "Gitmo", aka Guantanamo, the naval base in Cuba where the Bush administration imprisoned what it considered the 300 most dangerous and important Taliban and al-Qaeda men captured in Afghanistan. It seemed a good idea at the time. Military tribunals would dispose of the prisoners after they had given vital intelligence.

But nobody had any exit policy: faced with men who spoke numerous dialects of Arabic, the interrogators got nowhere. Hardly a shred of useful intelligence emerged from Guantanamo, but now the administration is seeking a catch-all device so that it can still put the prisoners before military tribunals. In the absence of any evidence of war crimes, they will try to have the men convicted of the retrospective crime merely of belonging to the Taliban or al-Qaeda. To hell with the Geneva Convention on POWs, in other words. (Even at the Nuremberg war crimes tribunal, nobody was charged retrospectively with SS membership.)

Or take John Walker Lindh, the Marin County boy who found himself fighting with the Taliban. The authorities have got themselves into an awful tangle. Lindh is charged with ten counts, the most important being that he conspired to kill Americans, while others allege that he aided terrorists. The prosecution concedes that "the bulk of the evidence . . . comes from Lindh's own admissions", yet the FBI omitted the usual formality of getting Lindh to sign any statement or to audio- or videotape his evidence. The defence insists he was kept naked and tied to a stretcher inside a shipping container for three days; pictures have emerged of just this. It also says he was denied a lawyer, and not told that his parents had one ready to fly to him in Afghanistan.

In other words, the case for the prosecution is crumbling before our eyes. Bush's attorney general, John Ashcroft, has a religious zeal for the death penalty, and promised either that or a sentence to life imprisonment for Lindh - but he now looks far from able to deliver. There is no evidence that Lindh conspired to kill Americans, and the only count likely to stick is that he was a member of the Taliban - which allows a maximum of ten years' imprisonment. He is now confined to his cell for 22 hours a day with no radio, television, videos, music, or contact with any other prisoners. But the top-class lawyer his parents have hired is likely to have a field day running rings around inept prosecutors with so weak a case.

By contrast, the one show trial likely to lead to success is that of Zacarias Moussaoui, the 33-year-old "20th hijacker" supposedly destined to fly the plane that ended up in a field in Pennsylvania - but who was arrested in August after a tip-off from a Minnesota flying school. It helps that Moussaoui is black (albeit a French national of Moroccan origin), and that he shows every sign of being a disturbed Muslim fanatic: last Monday, after a 50-minute rant, he fired his court-appointed lawyers. But even his case has serious implications: Moussaoui faces six conspiracy charges, four of which carry the death penalty. And all involved conspiracies relating to the atrocities of 11 September - when Moussaoui, much to the inconvenience of prosecutors, was already safely tucked up in a US jail.

However, I predict that he will be sentenced to death before the end of the year - that will satisfy some of the post-11 September bloodlust. In the meantime, Bush is allocating roughly $30bn to "homeland security", with $3.5bn going to ill-prepared states. But so far, the very notion of "homeland security" is a joke in Washington, with Ridge chaotically trying to co-ordinate a variety of warring government departments. Criticism of Bush himself for his handling of affairs since 11 September is still verboten: but that day is not far off, I'm afraid.