The European Court of Human Rights, overruling British courts, has ruled that the UK is stuck with Abu Qatada, once said to have been Osama bin Laden's right-hand man in Europe.
The radical cleric, arrested in the UK in 2002, was facing deportation to Jordan, where he was convicted in absentia for his role in 1999 and 2000 bomb plots. But the European court says some evidence against him may have been gained by torture, a human rights violation it calls significant enough to make deportation an abuse of his rights.
The ruling has enraged many Britons. If it stands, the tabloid Daily Mail says, Abu Qatada "will be freed in three months to a life on benefits with his wife and five children". The case also reminds us of the lingering problem of "war on terror" prisoners deprived of basic legal process.
The US base at Guantanamo still holds about 170 prisoners. The UK is still trying to deport half a dozen terror suspects. By "extraordinary rendition", the US has shipped others to states that use harsh interrogation.
These cases are by-products of the era of asymmetrical warfare. Governments holding such prisoners are unwilling, often for good reason, to free them, but can be equally reluctant to try them, because open trials could reveal secret intelligence sources or methods. Few other countries will consider accepting such people even if they can be extradited, unlike Abu Qatada.
In 2008, candidate Barack Obama pledged to close Guantanamo, but late last year the president signed into law a defence-spending bill that actually authorises the government to toss terror suspects, even US citizens, into indefinite military detention without charge or trial.
Indefinite detention without trial is a stain on ideals of human rights, and it becomes a rallying cry for other extremists. As with so many aspects of the "war on terror", this problem has no easy answers.
One possible solution may be found in the international war crimes court at Nuremberg after the Second World War. So far questions outnumber answers - under what laws could such trials proceed? - but the answers can be found if world leaders summon the political will to defend basic rights.