The death of Baha Musa in British military custody inside a detention centre in Basra in September 2003 was a disgraceful episode for which only one soldier has so far been punished.

Four law lords have now ruled that, contrary to the position taken by the Ministry of Defence, the Human Rights Act applies not only to the United Kingdom but also to areas outside the UK where the British military have jurisdictional control, such as a detention centre in a country where Britain is a postwar occupying power.

On that basis the soldiers breached the human rights of Mr Musa by beating him so severely that he suffered 93 separate injuries over a period of 36 hours, and died.

The House of Lords case is a legal precedent and for the family of Mr Musa it opens up the potential for substantial compensation, and, possibly, an independent public inquiry into the death.

However, paradoxically, the judgment should have no real impact on the way the Armed Forces carry out their business in an overseas operation.

Every soldier is already obliged to behave in accordance with the UK law, and that includes the Human Rights Act. Soldiers are not allowed to torture or abuse prisoners, because that would be a breach of the Geneva Convention, and if they assault an unarmed civilian in whatever circumstances, and the individual dies as a result, they know they could face criminal prosecution.

That has always been the case whether a soldier is serving in Northern Ireland or on the streets of Basra. Even before the Human Rights Act came into force in the UK, soldiers were bound by their rules of engagement, by the laws of armed conflict, and by their training to use violence proportionately, and to treat prisoners in a humane way.

So nothing has changed. But the significance of the House of Lords ruling is that the law lords have recognised, just as the head of the Army, General Sir Richard Dannatt, has publicly acknowledged, that Mr Musa’s case is a special one. He was brutally beaten while in British custody, and with the exception of one soldier, Corporal Donald Payne, those responsible have not been brought to book.

The law lords’ decision that the Human Rights Act has a legal bearing on the case further emphasises the fact that Mr Musa’s rights as a human being, as well as his rights as a prisoner, were abused.

The military hierarchy responsible for Operation Telic, the codename for the campaign in Iraq, need to explain why it was that soldiers from The Queen’s Lancashire Regiment who had arrested nine Iraqis during an arms search at a hotel in Basra, hooded their prisoners, forced them to adopt stress positions - knees bent and arms outstretched for 36 hours - apparently with the approval of brigade headquarters.

Why was it that no one at brigade or divisional level out in Iraq appeared to have remembered that in 1972 the Government of Edward Heath banned the use of hoods on prisoners, after a review of the treatment of IRA detainees by the military in Northern Ireland?

All soldiers receive legal training before they go on an operation. They are told about the Geneva Convention, they are given explicit instructions on the rules of engagement that govern when they are allowed to open fire, and they are told about the rules covering prisoner-handling.

Yet, it became clear from the court martial of five members of The Queen’s Lancashire Regiment and two from the Intelligence Corps, all charged in relation to the death of Mr Musa, that hooding, sleep deprivation and other pre-interrogation techniques that clearly breached the Geneva Convention, let alone the Human Rights Act, were sanctioned further up the chain of command. How could this have happened?

The protocols for handling prisoners are so well known, and so enshrined in law, that it is beyond credence that any member of the British Armed Forces considered it was lawful and acceptable to subject Mr Musa to the sort of abuse he suffered over 36 hours.

The senior hierarchy of the Army will have to come up with an explanation about what went wrong. The acquittal of six of the soldiers court martialled over the death of Mr Musa left unanswered the crucial questions: who was responsible for this state of affairs, why did brigade headquarters say hooding was acceptable, and who did cause Mr Musa’s death?

Explore Law

• Columnists

• Law Panel

• Law Reports

• Student Law

Times Recommends

• The best legal yarns this Christmas
• Legal school 'earned £1m by exploiting bar course'
• Axe may fall on 5,000 more City lawyers